Parts under `message/rfc822` don't seem to be parsed.

[ben221199]

For my IMAP project, I have written a IMAP server in Java, which uses an API written in PHP as backend. IMAP has some fetch attributes that can be used to get a part of a message, like BODY[], BODY[HEADER, BODY[1] and BODY[2.TEXT].

My Java IMAP server doesn't do anything with this. It just parses the IMAP protocol and sends a request that PHP can understand to my backend. There, I use this library to parse the parts of the message, based on the requested fetch attributes, and only return those requested attributes back to the IMAP server.

However, I have noted that this library only parses parts of multipart/* messages. When a message/rfc822 is present, it doesn't to this. This is fine for default behaviour, but because message/rfc822 is a special type, I would like an option to enable part parsing for this MIME type too. Now, I have to do tricks with detecting a message, getting its content, and reparsing the part on demand.

Also, next to isMultiPart(), I think a isRFC822Message() function is useful:

    public function isRFC822Message() : bool
    {
        // casting to bool, preg_match returns 1 for true
        return (bool) (\preg_match(
            '~message/rfc822~i',
            $this->getContentType()
        ));
    }

[zbateson]

Hi @ben221199 -- yeah, a part specifically defined as a 'message/rfc822' is just an attached 'message', we're correctly not identifying it as 'part' of the current message. Often attachments will include a separate message (forwards, or bounce-backs, etc...)

Your example looks good -- that function would mostly be useful to you I think though, I'm not sure we really want separate "isXXX" functions for every mime-type -- but if others agree with you, they can comment here... I'm not inherently against it, just you're the first to specifically want it.