[CentOS] email subject length issue

Wed Apr 12 21:41:31 UTC 2017
Alexander Dalloz <ad+lists at uni-x.org>

Am 12.04.2017 um 22:03 schrieb Richard:

[ ... ]

> A "Subject:" line is just a structured text line in the message body
> and MTAs (e.g., sendmail) don't do anything differently with it than
> any other line in a message body. The max length is 998 "characters".

No, the subject of a mail message is a defined field and part of the 
message header, not the body of the message. Just see RFC 5322. Message 
header and (optional) body are separated by an empty line. While there 
are specific rules for message header fields there are (nearly) none for 
the character flow of the mail body (MIME RFCs aside). The 998 character 
limit per line applies for both the header and the body.

> I suspect that your MUA or more likely procmail is where the
> truncation is taking place. I just did:
>    /bin/mailx -s"... 200+ character subject ..."
> on a C6/sendmail machine and it worked fine.

That turned out to be the case as the OP didn't cover folding of long 
header fields (RFC 5322 2.2.3).