Caution: The documentation you are viewing is
for an older version of Zend Framework.
You can find the documentation of the current version at:
Controlling the MIME Boundary - Zend_Mail
In a multipart message, a MIME boundary for separating the different parts of the message is normally generated at random. In some cases, however, you might want to specify the MIME boundary that is used. This can be done using the setMimeBoundary() method, as in the following example: