What is the exact MIME encodings used by CustomMailer?
If you send regular (non-HTML) mail, CustomMailer will send this with MIME type text/plain. For HTML mail, if the Alternate Text section is empty, CustomMailer will send this with MIME type text/html. If the Alternate Text section is not empty, CustomMailer will generate a multipart/alternative message, with the first section being the alternate text encoded as MIME type text/plain, followed by the text/html section. In any of the above cases if there are attachments, the overall message will be encoded multipart/mixed, followed by the message encoded as above, followed by one or more attachment sections encoded by the appropriate MIME types. If Content-IDs are used, the HTML section will be replaced by a a multipart/relative, the first part of which is the text/html portion followed by each of the content-ID sections encoded in their corresponding MIME types. The multimedia MIME types supported by CustomMailer are image/gif, image/jpeg, audio/wav, audio/aiff, audio/basic, and video/mp
