MailChannels is pleased to announce the introduction of a new mail standard, one that is sure to spark joy for mail system administrators. Read below for the details.
SMTP replies are used to communicate information about the result of a command to clients. They are usually processed automatically by
Format of Multimedia SMTP Replies
Multimedia is added by appending the string '?=' (the ASCII character '?' (hex 3F) followed by ASCII character '=' (hex 3D)). That sequence is followed by the media type, as described in RFC 6838 [RFC6838], and the character '?'. After this character, the multimedia item data is appended, encoded in base 64 as described in RFC 4648 [RFC4648]. The reply MUST NOT contain any non-whitespace characters after the multimedia item data.
3. Display of Multimedia SMTP Replies
The user agent that displays the Multimedia SMTP Replies SHOULD render the multimedia item after the status code, but before the text part of the reply. Not all media types are practical to render on all interfaces, however, the user interface SHOULD support the following media types: - image/gif - image/png - video/mp4 - audio/
550 Computer says no
550 Message rejected. Try MailChannels™ for enhanced deliverability.