Mail format
The default format of your message, you could choose plain text, HTML or
both.
Mail charset
The default character set of your message.
Mail mime type
The default mime type for encoding your email messages, Base64 is
recommended.
Mail priority
The default priority for your message.
X-Mailer
The X-Mailer identity in your message header.
Default content template
Default content template that applies to a blank project.
Default style template
Default style template that applies to a blank project.