Please fold header lines longer than 998 chars

[th-h]

RFC 5536 is the current Netnews Article Format standard. In "2.2. Header Fields", it has a MUST requirement that

Compliant software MUST NOT generate (but MAY accept) header field lines of more than 998 octets.

That's a requirement of RFC 5322 (Internet Message Format), too, in "2.1.1. Line Length Limits":

There are two limits that this specification places on the number of characters in a line. Each line of characters MUST be no more than 998 characters, and SHOULD be no more than 78 characters, excluding the CRLF.

XanaNews 1.21 does not do that, and least not for all headers, so posts with overly long headers will be rejected.

Steps to reproduce

XanaNews 1.21, downloaded from the Github release page.

1. "Post New Message" in a test group.
2. Use a very long subject, like "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat."
3. Posting fails with a server error message

Jun 12 11:40:43 thangorodrim nnrpd[20333]: scatha.ancalagon.de post failed Header line too long

Expected result would be for XanaNews to fold the header at FWS, as it does with a subject containing MIME encoded words.