Sylpheed produces forbidden code in the From:-header. I think it concerns all versions of Claws-Mail and Sylpheed. Here's an example: > From: "Wilhelm C. =?ISO-8859-1?Q?Sch=FCtze?=" <wil.c@web.de> > Newsgroups: de.comm.software.newsreader > Subject: Sylpheed kein (Sende-) Datum > X-Newsreader: Sylpheed 3.1.2 (GTK+ 2.24.6; i386-portbld-freebsd9.0) > Mime-Version: 1.0 > Content-Type: text/plain; charset=ISO-8859-1 > Content-Transfer-Encoding: quoted-printable > > Hi, ... [<jgutir$103$2@news.albasani.net>] Sylpheed puts the name in double quotes and encodes the non-ASCII character "ΓΌ" (ISO-8859-1 FCh) inside the quotes. That is a violation of RFC 2047. RFC 2047 part 5 (3) says: + [...] + An 'encoded-word' MUST NOT appear within a 'quoted-string'. I think the use of double quotes in the From:-header is not a good idea. RFC 5322 part 3.2.4 reads: Quoted Strings Strings of characters that include characters other than those allowed in atoms can be represented in a quoted string format, where the characters are surrounded by quote (DQUOTE, ASCII value 34) characters. But there is a limitation in RFC 5322 part 2.1 Note: This document specifies that messages are made up of characters in the US-ASCII range of 1 through 127. There are other documents, specifically the MIME document series ([RFC2045], [RFC2046], [RFC2047], [RFC2049], [RFC4288], [RFC4289]), that extend this specification to allow for values outside of that range. Discussion of those mechanisms is not within the scope of this specification. That means you cannot use ASCII-characters > 127 in the From:-header. So there is no reason working with double quotes. Watch this too: http://forums.mozillazine.org/viewtopic.php?t=318281
It would be nice of you to actually test Claws Mail before reporting bugs affecting unrelated software to our bug tracker.