javax.mail.internet
Class MimeBodyPart

java.lang.Object
  javax.mail.BodyPart
      javax.mail.internet.MimeBodyPart

All Implemented Interfaces:

MimePart, Part

public class MimeBodyPart

extends BodyPart

implements MimePart

This class represents a MIME body part. It implements the BodyPart abstract class and the MimePart interface. MimeBodyParts are contained in MimeMultipart objects.

MimeBodyPart uses the InternetHeaders class to parse and store the headers of that body part.

A note on RFC 822 and MIME headers

RFC 822 header fields must contain only US-ASCII characters. MIME allows non ASCII characters to be present in certain portions of certain headers, by encoding those characters. RFC 2047 specifies the rules for doing this. The MimeUtility class provided in this package can be used to to achieve this. Callers of the setHeader, addHeader, and addHeaderLine methods are responsible for enforcing the MIME requirements for the specified headers. In addition, these header fields must be folded (wrapped) before being sent if they exceed the line length limitation for the transport (1000 bytes for SMTP). Received headers may have been folded. The application is responsible for folding and unfolding headers as appropriate.

Author:

John Mani, Bill Shannon

See Also:

Part, MimePart, MimeUtility

Field Summary

protected byte[]	content Byte array that holds the bytes of the content of this Part.
protected java.io.InputStream	contentStream If the data for this body part was supplied by an InputStream that implements the SharedInputStream interface, contentStream is another such stream representing the content of this body part.
protected DataHandler	dh The DataHandler object representing this Part's content.
protected InternetHeaders	headers The InternetHeaders object that stores all the headers of this body part.

Fields inherited from class javax.mail.BodyPart

parent

Fields inherited from interface javax.mail.Part

ATTACHMENT, INLINE

Constructor Summary

MimeBodyPart()
An empty MimeBodyPart object is created.

MimeBodyPart(java.io.InputStream is)
Constructs a MimeBodyPart by reading and parsing the data from the specified input stream.

MimeBodyPart(InternetHeaders headers, byte[] content)
Constructs a MimeBodyPart using the given header and content bytes.

Method Summary

void	addHeader(java.lang.String name, java.lang.String value) Add this value to the existing values for this header_name.
void	addHeaderLine(java.lang.String line) Add a header line to this body part
java.util.Enumeration	getAllHeaderLines() Get all header lines as an Enumeration of Strings.
java.util.Enumeration	getAllHeaders() Return all the headers from this Message as an Enumeration of Header objects.
java.lang.Object	getContent() Return the content as a java object.
java.lang.String	getContentID() Returns the value of the "Content-ID" header field.
java.lang.String[]	getContentLanguage() Get the languages specified in the Content-Language header of this MimePart.
java.lang.String	getContentMD5() Return the value of the "Content-MD5" header field.
protected java.io.InputStream	getContentStream() Produce the raw bytes of the content.
java.lang.String	getContentType() Returns the value of the RFC 822 "Content-Type" header field.
DataHandler	getDataHandler() Return a DataHandler for this body part's content.
java.lang.String	getDescription() Returns the "Content-Description" header field of this body part.
java.lang.String	getDisposition() Returns the value of the "Content-Disposition" header field.
java.lang.String	getEncoding() Returns the content transfer encoding from the "Content-Transfer-Encoding" header field.
java.lang.String	getFileName() Get the filename associated with this body part.
java.lang.String[]	getHeader(java.lang.String name) Get all the headers for this header_name.
java.lang.String	getHeader(java.lang.String name, java.lang.String delimiter) Get all the headers for this header name, returned as a single String, with headers separated by the delimiter.
java.io.InputStream	getInputStream() Return a decoded input stream for this body part's "content".
int	getLineCount() Return the number of lines for the content of this Part.
java.util.Enumeration	getMatchingHeaderLines(java.lang.String[] names) Get matching header lines as an Enumeration of Strings.
java.util.Enumeration	getMatchingHeaders(java.lang.String[] names) Return matching headers from this Message as an Enumeration of Header objects.
java.util.Enumeration	getNonMatchingHeaderLines(java.lang.String[] names) Get non-matching header lines as an Enumeration of Strings.
java.util.Enumeration	getNonMatchingHeaders(java.lang.String[] names) Return non-matching headers from this Message as an Enumeration of Header objects.
java.io.InputStream	getRawInputStream() Return an InputStream to the raw data with any Content-Transfer-Encoding intact.
int	getSize() Return the size of the content of this body part in bytes.
boolean	isMimeType(java.lang.String mimeType) Is this Part of the specified MIME type?
void	removeHeader(java.lang.String name) Remove all headers with this name.
void	setContent(Multipart mp) This method sets the body part's content to a Multipart object.
void	setContent(java.lang.Object o, java.lang.String type) A convenience method for setting this body part's content.
void	setContentID(java.lang.String cid) Set the "Content-ID" header field of this body part.
void	setContentLanguage(java.lang.String[] languages) Set the Content-Language header of this MimePart.
void	setContentMD5(java.lang.String md5) Set the "Content-MD5" header field of this body part.
void	setDataHandler(DataHandler dh) This method provides the mechanism to set this body part's content.
void	setDescription(java.lang.String description) Set the "Content-Description" header field for this body part.
void	setDescription(java.lang.String description, java.lang.String charset) Set the "Content-Description" header field for this body part.
void	setDisposition(java.lang.String disposition) Set the "Content-Disposition" header field of this body part.
void	setFileName(java.lang.String filename) Set the filename associated with this body part, if possible.
void	setHeader(java.lang.String name, java.lang.String value) Set the value for this header_name.
void	setText(java.lang.String text) Convenience method that sets the given String as this part's content, with a MIME type of "text/plain".
void	setText(java.lang.String text, java.lang.String charset) Convenience method that sets the given String as this part's content, with a MIME type of "text/plain" and the specified charset.
protected void	updateHeaders() Examine the content of this body part and update the appropriate MIME headers.
void	writeTo(java.io.OutputStream os) Output the body part as an RFC 822 format stream.

Methods inherited from class javax.mail.BodyPart

getParent

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

dh

protected DataHandler dh

The DataHandler object representing this Part's content.

content

protected byte[] content

Byte array that holds the bytes of the content of this Part.

contentStream

protected java.io.InputStream contentStream

If the data for this body part was supplied by an InputStream that implements the SharedInputStream interface, contentStream is another such stream representing the content of this body part. In this case, content will be null.

Since:

JavaMail 1.2

headers

protected InternetHeaders headers

The InternetHeaders object that stores all the headers of this body part.

Constructor Detail

MimeBodyPart

public MimeBodyPart()

An empty MimeBodyPart object is created. This body part maybe filled in by a client constructing a multipart message.

MimeBodyPart

public MimeBodyPart(java.io.InputStream is)
             throws MessagingException

Constructs a MimeBodyPart by reading and parsing the data from the specified input stream. The parser consumes data till the end of the given input stream. The input stream must start at the beginning of a valid MIME body part and must terminate at the end of that body part.

Note that the "boundary" string that delimits body parts must not be included in the input stream. The intention is that the MimeMultipart parser will extract each body part's bytes from a multipart stream and feed them into this constructor, without the delimiter strings.

Parameters:

is - the body part Input Stream

MimeBodyPart

public MimeBodyPart(InternetHeaders headers,
                    byte[] content)
             throws MessagingException

Constructs a MimeBodyPart using the given header and content bytes.

Used by providers.

Parameters:

headers - The header of this part

content - bytes representing the body of this part.

Method Detail

getSize

public int getSize()
            throws MessagingException

Return the size of the content of this body part in bytes. Return -1 if the size cannot be determined.

Note that this number may not be an exact measure of the content size and may or may not account for any transfer encoding of the content.

This implementation returns the size of the content array (if not null), or, if contentStream is not null, and the available method returns a positive number, it returns that number as the size. Otherwise, it returns -1.

Specified by:

getSize in interface Part

Returns:

size in bytes, or -1 if not known

Throws:

MessagingException

getLineCount

public int getLineCount()
                 throws MessagingException

Return the number of lines for the content of this Part. Return -1 if this number cannot be determined.

Note that this number may not be an exact measure of the content length and may or may not account for any transfer encoding of the content.

This implementation returns -1.

Specified by:

getLineCount in interface Part

Returns:

number of lines, or -1 if not known

Throws:

MessagingException

getContentType

public java.lang.String getContentType()
                                throws MessagingException

Returns the value of the RFC 822 "Content-Type" header field. This represents the content type of the content of this body part. This value must not be null. If this field is unavailable, "text/plain" should be returned.

This implementation uses getHeader(name) to obtain the requisite header field.

Specified by:

getContentType in interface Part

Returns:

Content-Type of this body part

Throws:

MessagingException

See Also:

DataHandler

isMimeType

public boolean isMimeType(java.lang.String mimeType)
                   throws MessagingException

Is this Part of the specified MIME type? This method compares only the primaryType and subType. The parameters of the content types are ignored.

For example, this method will return true when comparing a Part of content type "text/plain" with "text/plain; charset=foobar".

If the subType of mimeType is the special character '*', then the subtype is ignored during the comparison.

Specified by:

isMimeType in interface Part

Throws:

MessagingException

getDisposition

public java.lang.String getDisposition()
                                throws MessagingException

Returns the value of the "Content-Disposition" header field. This represents the disposition of this part. The disposition describes how the part should be presented to the user.

If the Content-Disposition field is unavailable, null is returned.

This implementation uses getHeader(name) to obtain the requisite header field.

Specified by:

getDisposition in interface Part

Returns:

disposition of this part, or null if unknown

Throws:

MessagingException

See Also:

headers

setDisposition

public void setDisposition(java.lang.String disposition)
                    throws MessagingException

Set the "Content-Disposition" header field of this body part. If the disposition is null, any existing "Content-Disposition" header field is removed.

Specified by:

setDisposition in interface Part

Parameters:

disposition - disposition of this part

Throws:

IllegalWriteException - if the underlying implementation does not support modification

java.lang.IllegalStateException - if this body part is obtained from a READ_ONLY folder.

MessagingException

See Also:

Part.ATTACHMENT, Part.INLINE, Part.setFileName(java.lang.String)

getEncoding

public java.lang.String getEncoding()
                             throws MessagingException

Returns the content transfer encoding from the "Content-Transfer-Encoding" header field. Returns null if the header is unavailable or its value is absent.

This implementation uses getHeader(name) to obtain the requisite header field.

Specified by:

getEncoding in interface MimePart

Returns:

content-transfer-encoding

Throws:

MessagingException

See Also:

headers

getContentID

public java.lang.String getContentID()
                              throws MessagingException

Returns the value of the "Content-ID" header field. Returns null if the field is unavailable or its value is absent.

This implementation uses getHeader(name) to obtain the requisite header field.

Specified by:

getContentID in interface MimePart

Returns:

content-ID

Throws:

MessagingException

setContentID

public void setContentID(java.lang.String cid)
                  throws MessagingException

Set the "Content-ID" header field of this body part. If the cid parameter is null, any existing "Content-ID" is removed.

Throws:

IllegalWriteException - if the underlying implementation does not support modification

java.lang.IllegalStateException - if this body part is obtained from a READ_ONLY folder.

MessagingException

Since:

JavaMail 1.3

getContentMD5

public java.lang.String getContentMD5()
                               throws MessagingException

Return the value of the "Content-MD5" header field. Returns null if this field is unavailable or its value is absent.

This implementation uses getHeader(name) to obtain the requisite header field.

Specified by:

getContentMD5 in interface MimePart

Returns:

content-MD5

Throws:

MessagingException

setContentMD5

public void setContentMD5(java.lang.String md5)
                   throws MessagingException

Set the "Content-MD5" header field of this body part.

Specified by:

setContentMD5 in interface MimePart

Parameters:

md5 - the MD5 value

Throws:

IllegalWriteException - if the underlying implementation does not support modification

java.lang.IllegalStateException - if this body part is obtained from a READ_ONLY folder.

MessagingException

getContentLanguage

public java.lang.String[] getContentLanguage()
                                      throws MessagingException

Get the languages specified in the Content-Language header of this MimePart. The Content-Language header is defined by RFC 1766. Returns null if this header is not available or its value is absent.

This implementation uses getHeader(name) to obtain the requisite header field.

Specified by:

getContentLanguage in interface MimePart

Throws:

MessagingException

setContentLanguage

public void setContentLanguage(java.lang.String[] languages)
                        throws MessagingException

Set the Content-Language header of this MimePart. The Content-Language header is defined by RFC 1766.

Specified by:

setContentLanguage in interface MimePart

Parameters:

languages - array of language tags

Throws:

MessagingException

getDescription

public java.lang.String getDescription()
                                throws MessagingException

Returns the "Content-Description" header field of this body part. This typically associates some descriptive information with this part. Returns null if this field is unavailable or its value is absent.

If the Content-Description field is encoded as per RFC 2047, it is decoded and converted into Unicode. If the decoding or conversion fails, the raw data is returned as is.

This implementation uses getHeader(name) to obtain the requisite header field.

Specified by:

getDescription in interface Part

Returns:

content description

Throws:

MessagingException

setDescription

public void setDescription(java.lang.String description)
                    throws MessagingException

Set the "Content-Description" header field for this body part. If the description parameter is null, then any existing "Content-Description" fields are removed.

If the description contains non US-ASCII characters, it will be encoded using the platform's default charset. If the description contains only US-ASCII characters, no encoding is done and it is used as is.

Note that if the charset encoding process fails, a MessagingException is thrown, and an UnsupportedEncodingException is included in the chain of nested exceptions within the MessagingException.

Specified by:

setDescription in interface Part

Parameters:

description - content description

Throws:

IllegalWriteException - if the underlying implementation does not support modification

java.lang.IllegalStateException - if this body part is obtained from a READ_ONLY folder.

MessagingException - otherwise; an UnsupportedEncodingException may be included in the exception chain if the charset conversion fails.

setDescription

public void setDescription(java.lang.String description,
                           java.lang.String charset)
                    throws MessagingException

Set the "Content-Description" header field for this body part. If the description parameter is null, then any existing "Content-Description" fields are removed.

If the description contains non US-ASCII characters, it will be encoded using the specified charset. If the description contains only US-ASCII characters, no encoding is done and it is used as is.

Note that if the charset encoding process fails, a MessagingException is thrown, and an UnsupportedEncodingException is included in the chain of nested exceptions within the MessagingException.

Parameters:

description - Description

charset - Charset for encoding

Throws:

IllegalWriteException - if the underlying implementation does not support modification

java.lang.IllegalStateException - if this body part is obtained from a READ_ONLY folder.

MessagingException - otherwise; an UnsupportedEncodingException may be included in the exception chain if the charset conversion fails.

getFileName

public java.lang.String getFileName()
                             throws MessagingException

Get the filename associated with this body part.

Returns the value of the "filename" parameter from the "Content-Disposition" header field of this body part. If its not available, returns the value of the "name" parameter from the "Content-Type" header field of this body part. Returns null if both are absent.

Specified by:

getFileName in interface Part

Returns:

filename

Throws:

MessagingException

setFileName

public void setFileName(java.lang.String filename)
                 throws MessagingException

Set the filename associated with this body part, if possible.

Sets the "filename" parameter of the "Content-Disposition" header field of this body part.

Specified by:

setFileName in interface Part

Parameters:

filename - Filename to associate with this part

Throws:

IllegalWriteException - if the underlying implementation does not support modification

java.lang.IllegalStateException - if this body part is obtained from a READ_ONLY folder.

MessagingException

getInputStream

public java.io.InputStream getInputStream()
                                   throws java.io.IOException,
                                          MessagingException

Return a decoded input stream for this body part's "content".

This implementation obtains the input stream from the DataHandler. That is, it invokes getDataHandler().getInputStream();

Specified by:

getInputStream in interface Part

Returns:

an InputStream

Throws:

MessagingException

java.io.IOException - this is typically thrown by the DataHandler. Refer to the documentation for javax.activation.DataHandler for more details.

See Also:

getContentStream(), DataHandler.getInputStream()

getContentStream

protected java.io.InputStream getContentStream()
                                        throws MessagingException

Produce the raw bytes of the content. This method is used when creating a DataHandler object for the content. Subclasses that can provide a separate input stream for just the Part content might want to override this method.

Throws:

MessagingException

See Also:

content, MimeMessage.getContentStream()

getRawInputStream

public java.io.InputStream getRawInputStream()
                                      throws MessagingException

Return an InputStream to the raw data with any Content-Transfer-Encoding intact. This method is useful if the "Content-Transfer-Encoding" header is incorrect or corrupt, which would prevent the getInputStream method or getContent method from returning the correct data. In such a case the application may use this method and attempt to decode the raw data itself.

This implementation simply calls the getContentStream method.

Throws:

MessagingException

Since:

JavaMail 1.2

See Also:

getInputStream(), getContentStream()

getDataHandler

public DataHandler getDataHandler()
                           throws MessagingException

Return a DataHandler for this body part's content.

The implementation provided here works just like the the implementation in MimeMessage.

Specified by:

getDataHandler in interface Part

Returns:

DataHandler for the content

Throws:

MessagingException

See Also:

MimeMessage.getDataHandler()

getContent

public java.lang.Object getContent()
                            throws java.io.IOException,
                                   MessagingException

Return the content as a java object. The type of the object returned is of course dependent on the content itself. For example, the native format of a text/plain content is usually a String object. The native format for a "multipart" content is always a Multipart subclass. For content types that are unknown to the DataHandler system, an input stream is returned as the content.

This implementation obtains the content from the DataHandler. That is, it invokes getDataHandler().getContent();

Specified by:

getContent in interface Part

Returns:

Object

Throws:

MessagingException

java.io.IOException - this is typically thrown by the DataHandler. Refer to the documentation for javax.activation.DataHandler for more details.

See Also:

DataHandler.getContent()

setDataHandler

public void setDataHandler(DataHandler dh)
                    throws MessagingException

This method provides the mechanism to set this body part's content. The given DataHandler object should wrap the actual content.

Specified by:

setDataHandler in interface Part

Parameters:

dh - The DataHandler for the content

Throws:

IllegalWriteException - if the underlying implementation does not support modification

java.lang.IllegalStateException - if this body part is obtained from a READ_ONLY folder.

MessagingException

setContent

public void setContent(java.lang.Object o,
                       java.lang.String type)
                throws MessagingException

A convenience method for setting this body part's content.

The content is wrapped in a DataHandler object. Note that a DataContentHandler class for the specified type should be available to the JavaMail implementation for this to work right. That is, to do setContent(foobar, "application/x-foobar"), a DataContentHandler for "application/x-foobar" should be installed. Refer to the Java Activation Framework for more information.

Specified by:

setContent in interface Part

Parameters:

o - the content object

type - Mime type of the object

Throws:

IllegalWriteException - if the underlying implementation does not support modification of existing values

java.lang.IllegalStateException - if this body part is obtained from a READ_ONLY folder.

MessagingException

setText

public void setText(java.lang.String text)
             throws MessagingException

Convenience method that sets the given String as this part's content, with a MIME type of "text/plain". If the string contains non US-ASCII characters, it will be encoded using the platform's default charset. The charset is also used to set the "charset" parameter.

Note that there may be a performance penalty if text is large, since this method may have to scan all the characters to determine what charset to use.

If the charset is already known, use the setText() version that takes the charset parameter.

Specified by:

setText in interface MimePart

Throws:

MessagingException

See Also:

setText(String text, String charset)

setText

public void setText(java.lang.String text,
                    java.lang.String charset)
             throws MessagingException

Convenience method that sets the given String as this part's content, with a MIME type of "text/plain" and the specified charset. The given Unicode string will be charset-encoded using the specified charset. The charset is also used to set the "charset" parameter.

Specified by:

setText in interface MimePart

Throws:

MessagingException

setContent

public void setContent(Multipart mp)
                throws MessagingException

This method sets the body part's content to a Multipart object.

Specified by:

setContent in interface Part

Parameters:

mp - The multipart object that is the Message's content

Throws:

IllegalWriteException - if the underlying implementation does not support modification of existing values.

java.lang.IllegalStateException - if this body part is obtained from a READ_ONLY folder.

MessagingException

writeTo

public void writeTo(java.io.OutputStream os)
             throws java.io.IOException,
                    MessagingException

Output the body part as an RFC 822 format stream.

Specified by:

writeTo in interface Part

Throws:

MessagingException

java.io.IOException - if an error occurs writing to the stream or if an error is generated by the javax.activation layer.

See Also:

DataHandler.writeTo(java.io.OutputStream)

getHeader

public java.lang.String[] getHeader(java.lang.String name)
                             throws MessagingException

Get all the headers for this header_name. Note that certain headers may be encoded as per RFC 2047 if they contain non US-ASCII characters and these should be decoded.

Specified by:

getHeader in interface Part

Parameters:

name - name of header

Returns:

array of headers

Throws:

MessagingException

See Also:

MimeUtility

getHeader

public java.lang.String getHeader(java.lang.String name,
                                  java.lang.String delimiter)
                           throws MessagingException

Get all the headers for this header name, returned as a single String, with headers separated by the delimiter. If the delimiter is null, only the first header is returned.

Specified by:

getHeader in interface MimePart

Parameters:

name - the name of this header

delimiter - delimiter between fields in returned string

Returns:

the value fields for all headers with this name

Throws:

MessagingException

setHeader

public void setHeader(java.lang.String name,
                      java.lang.String value)
               throws MessagingException

Set the value for this header_name. Replaces all existing header values with this new value. Note that RFC 822 headers must contain only US-ASCII characters, so a header that contains non US-ASCII characters must be encoded as per the rules of RFC 2047.

Specified by:

setHeader in interface Part

Parameters:

name - header name

value - header value

Throws:

MessagingException

See Also:

MimeUtility

addHeader

public void addHeader(java.lang.String name,
                      java.lang.String value)
               throws MessagingException

Add this value to the existing values for this header_name. Note that RFC 822 headers must contain only US-ASCII characters, so a header that contains non US-ASCII characters must be encoded as per the rules of RFC 2047.

Specified by:

addHeader in interface Part

Parameters:

name - header name

value - header value

Throws:

MessagingException

See Also:

MimeUtility

removeHeader

public void removeHeader(java.lang.String name)
                  throws MessagingException

Remove all headers with this name.

Specified by:

removeHeader in interface Part

Parameters:

name - the name of this header

Throws:

MessagingException

getAllHeaders

public java.util.Enumeration getAllHeaders()
                                    throws MessagingException

Return all the headers from this Message as an Enumeration of Header objects.

Specified by:

getAllHeaders in interface Part

Returns:

enumeration of Header objects

Throws:

MessagingException

getMatchingHeaders

public java.util.Enumeration getMatchingHeaders(java.lang.String[] names)
                                         throws MessagingException

Return matching headers from this Message as an Enumeration of Header objects.

Specified by:

getMatchingHeaders in interface Part

Returns:

enumeration of Header objects

Throws:

MessagingException

getNonMatchingHeaders

public java.util.Enumeration getNonMatchingHeaders(java.lang.String[] names)
                                            throws MessagingException

Return non-matching headers from this Message as an Enumeration of Header objects.

Specified by:

getNonMatchingHeaders in interface Part

Returns:

enumeration of Header objects

Throws:

MessagingException

addHeaderLine

public void addHeaderLine(java.lang.String line)
                   throws MessagingException

Add a header line to this body part

Specified by:

addHeaderLine in interface MimePart

Throws:

MessagingException

getAllHeaderLines

public java.util.Enumeration getAllHeaderLines()
                                        throws MessagingException

Get all header lines as an Enumeration of Strings. A Header line is a raw RFC 822 header line, containing both the "name" and "value" field.

Specified by:

getAllHeaderLines in interface MimePart

Throws:

MessagingException

getMatchingHeaderLines

public java.util.Enumeration getMatchingHeaderLines(java.lang.String[] names)
                                             throws MessagingException

Get matching header lines as an Enumeration of Strings. A Header line is a raw RFC 822 header line, containing both the "name" and "value" field.

Specified by:

getMatchingHeaderLines in interface MimePart

Throws:

MessagingException

getNonMatchingHeaderLines

public java.util.Enumeration getNonMatchingHeaderLines(java.lang.String[] names)
                                                throws MessagingException

Get non-matching header lines as an Enumeration of Strings. A Header line is a raw RFC 822 header line, containing both the "name" and "value" field.

Specified by:

getNonMatchingHeaderLines in interface MimePart

Throws:

MessagingException

updateHeaders

protected void updateHeaders()
                      throws MessagingException

Examine the content of this body part and update the appropriate MIME headers. Typical headers that get set here are Content-Type and Content-Transfer-Encoding. Headers might need to be updated in two cases:
- A message being crafted by a mail application will certainly need to activate this method at some point to fill up its internal headers.
- A message read in from a Store will have obtained all its headers from the store, and so doesn't need this. However, if this message is editable and if any edits have been made to either the content or message structure, we might need to resync our headers.
In both cases this method is typically called by the Message.saveChanges method.

Throws:

MessagingException