How can I add a custom part to emails How can I add create a multi-part email in D7?  I need to add custom part to an email.

I am trying to use hook_mail_alter to append a new content type.  The content type is Content-Type: text/calendar.  I can't figure out where to add it in the $message array.

I have tried mimemail but it seems to disregard my SMTP settings.
You could use hook_mail_alter to alter the email message before sending it out. you could change or alter the email body, sender, attachments....etc as you wish