The class can also be used to create new multipart messages with alternative content, such a message with both plain text and styled HTML text. Once a message has been created, files can be attached to the message and the application can make any other changes that are needed. The class provides complete access to all headers and content in a multipart message, including the ability to create your own custom headers and make modifications to specific sections.
Initialize
Initialize an instance of the class, validating the development
license. This method must be called before any properties are
changed or any other methods in this class are called by the
application.
ComposeMessage
Compose a new message using the specified header field values and
content. Using this method, you can create a message with the From,
To, Cc and Subject headers already defined, along with any text for
the message. You can also optionally provide both plain and styled
HTML text versions of the message and the method will automatically
create a multipart message.
ClearMessage
Releases the memory allocated for the current message, including
any file attachments, and creates a new, empty message.
Uninitialize
Release any resources that have been allocated for the current
process. This is the last method call that the application should
make prior to terminating.
Each message has one or more headers fields which provide information about the contents of the message. For example, the "From" header field specifies the email address of the person who sent the message. There are a fairly large number of header fields defined by the MIME standard, and applications can also create their own custom headers if they wish. The class gives the application complete access to the header fields in a message. Headers can be examined, modified, created or removed from the message as needed.
GetHeader
This method copies the value of a header field into a string buffer
that you provide. To return the value of the common header fields
such as "From", "To" and "Subject", you should specify a message
part of zero by setting the MessagePart property.
GetFirstHeader
This method returns the value of the first header defined in the
current message part, copying it into the string buffer that you
provide. This is used in conjunction with the GetNextHeader method
to enumerate all of the headers that have been defined.
GetNextHeader
This method returns the value of the next header defined in the
current message part. It should be called in a loop until it
returns a value of zero (False) which indicates that the last
message header has been returned.
SetHeader
Set a message header field to the specified value in the current
message part. If the value is an empty string, the message header
will be deleted from the message.
DeleteHeader
Delete the specified message header from the current message
part.
The content or body of a message contains the text that is to be read or processed by the recipient. It may be a simple, plain text message or it may be more complex, such as a combination of plain and styled HTML text or the data for a file attachment. The class provides complete access to the contents of the message, enabling the application to modify, extract, replace or delete specific sections of the message.
Message
This property returns the current message, including the headers
and all message parts, as a string. Setting this property will
cause the current message to be cleared and replaced by the new
value. The string contents must follow the standard specifications
for a message. If the property is set to an empty string, the
current message is cleared.
Text
This property returns the body of the current message part. Setting
this property replaces the entire message body with the new
text.
Most typical messages contain a single part, which consists of the message headers followed by the contents of the message. However, when files are attached to a message or alternative content types such as HTML are used, a more complex multipart message is required. With a multipart message, the contents of the message are split into logical sections with each section containing a specific part of the message. For example, when a file is attached to a message, one part of the message contains the text to be read by the recipient and another part contains the data for the file.
The first of a multipart message is called part 0, and contains the main header block. This is what defines the headers that you are most familiar with, such as "From", "To" and "Subject". The body of this message part is typically a plain text message that indicates that this is a multipart message. This is done for the benefit of older mail clients that cannot parse MIME messages correctly. Next part, part 1, typically contains the actual body of the message that would be displayed by the mail client. Additional parts may contain file attachments and other information. In the case of a multipart message that contains both plain and styled HTML text versions of a message, part 1 is typically the plain text version of the message while part 2 contains the HTML version. The mail client can then make a decision based on its own configuration as to which version of the message it displays.
Part
This property returns the current message part index. All messages
have at least one part, which consists of one or more header
fields, followed by the body of the message. The default part, part
0, refers to the main message header and body. If the message
contains multiple parts (as with a message that contains one or
more attached files), this property can be set to refer to that
specific part of the message.
PartCount
This property returns the number of parts in the current message.
All messages have at least one part, referenced as part 0.
Multipart messages will consist of additional parts which may be
accessed by setting the Part property.
CreatePart
Create a new, empty message part. If the message was not originally
a multipart message, it will be restructured into one. Otherwise,
the new part is simply added to the end of the message. This method
will cause the current message part to change to the new part that
was just created.
DeletePart
Delete the message part from the message. If the message part is in
the middle of the message, it will cause the subsequent parts of
the message to be reordered. You should not delete part zero to
delete a message; use the DeleteMessage method instead.
The class can be used to import existing messages from a text file and export messages to a text file. Once the message has been parsed, the application can examine or modify specific parts of the message. The following methods are provided to import and export the contents of a message:
ImportMessage
The simplest method of importing a message, this method reads the
contents of the specified file and imports it into the current
message. Note that the current message contents will be overwritten
with the imported message.
ExportMessage
This method exports the current message to a file. When using this
method, only certain headers are exported and they may be
reordered. To force all headers to be included in the message or to
preserve the order of the headers, set the Options property.
In addition to simple text messages, one or more files can be attached to a message. The process of attaching a file involves creating a multipart message, encoding the contents of the file and then including that encoded data in the message. The following methods are provided to manage files attached to the message, as well as attach files to an existing message:
Attachment
A property which returns the name of a file attachment in the
current message part. This property serves two purposes, to
determine if the current message part contains a file attachment,
and if so, what file name should be used when extracting that
attachment.
AttachFile
This method attaches the contents of the file to the message. The
file will be attached using the specified encoding algorithm and
will become the current message part. If the message is not a
multipart message, it will be converted to one; if it already is a
multipart message, the attachment will be added to the end of the
message.
AttachData
This method works in similar fashion to AttachFile, except that
instead of the contents of a file, the data in a memory buffer will
be attached to the message. If the message is not a multipart
message, it will be converted to one; if it already is a multipart
message, the attachment will be added to the end of the
message.
AttachImage
This method attaches an inline image file to the message. It is
similar to the AttachFile method, except that the image is designed
to be referenced as an embedded graphic in an HTML message. This
method will automatically set the correct header values for an
inline image attachment, and enables the developer to specify a
content ID which is used in the HTML message.
ExtractFile
Extract the file attachment in the current message part, storing
the contents in a file. The attachment will automatically be
decoded if necessary. This method also recognizes uuencoded
attachments that are embedded directly in the body of the message,
rather than using the standard MIME format.
The Mail Message class also has methods which are designed to make it easier to work with email addresses. Addresses are typically in the format of "user@domain.com" however additional information can be included with the address, such as the user's name or other comments that aren't part of the address itself. The class can parse these addresses for you, returning them in a format that is suitable for use with other protocols such as the SMTP class.
ParseAddress
Parse an email address that may include an address without a domain
name or comments in the address, such as the user's name. For
example, the From header field may return an address like "Joe
Smith <joe@bigcorp.com>"; this method would parse the address
and return "joe@bigcorp.com", the actual address for the user.
Recipient
It is common for certain headers to contain multiple addresses
separated by a comma. These addresses may also include comments
such as the user's name. This property array returns a list of
valid addresses defined in the current message. For example, the To
header field may contain "Tom Jones <tom@bigcorp.com>, Jerry
Lewis <jerry@bigcorp.com>"; this property array would return
"tom@bigcorp.com" and "jerry@bigcorp.com" as the two addresses
listed. The total number of addresses that are available is
returned by the Recipients property.
The Mail Message class has a collection of methods which makes it simple for an application to store a group of messages together in a single file, search for and retrieve specific message. The collection of messages is referred to as a "message store" and messages may either be stored in a plaintext format or in a compressed binary format.
OpenStore
This method is used to open an existing message store or creates a
new storage file. If a storage file has been opened previously, it
will be closed and the new storage file will be opened. The storage
files may either be plaintext, or stored in a compressed format. It
also supports opening storage files in the UNIX mbox format.
StoreSize
This property returns the total number of messages that currently
in the message store, including deleted messages. Each message is
referred to by an integer which is its index into the storage
file.
StoreIndex
This property specifies the current message index into the storage
file. Messages are identified by an integer value that starts at
one for the first message and increments for each additional
message in the storage file. If no message store has been opened,
this property will return a value of zero. Changing the value of
this property changes the current message index for the message
store.
FindMessage
An application can search the message store for messages that match
any header value. Searches can be complete or partial, and may be
case-sensitive or case-insensitive. For example, this method can be
used to enumerate all of the messages in the storage file that were
sent by a specific user or match a specific subject.
ReadStore
This method reads a message from the storage file and replaces the
current message. If the application modifies the message, it can
replace the message in the storage file or discard the changes.
WriteStore
This method writes the current message to the message store. Note
that the message store must be opened for write access, and the
message will always be appended to the storage file. The StoreIndex
property is updated with the index value for the new message.
DeleteMessage
This method flags a message for deletion from the message store.
Once a message has been flagged for deletion, it may no longer be
accessed by the application. When the storage file is closed, the
contents of the deleted message will be removed from the file.
ReplaceMessage
This method replaces an existing message in the storage file,
overwriting it with the current message. Unlike many of the other
methods which do not permit the application to reference a deleted
message, this method can be used to replace a previously deleted
message.
CloseStore
The message store must be closed when the application has finished
accessing it. This method updates the storage file with any
changes, purges all deleted messages and closes the storage file.
If the storage file is locked for exclusive access, this method
will release that lock, allowing another process to open the
file