The stars aligned recently such that I sent someone a message that contained a line similar to this in the message body:
From glenn@usg.edu Thu Jun 20 16:48:11 2002
(Except that there wasn't that space character *before* the From; I've added it here to avoid any problems with this message).
Dovecot wrote a copy of the message in my "sent mail" folder under the direction of my imap client. But when I went back to *read* that folder (still through Dovecot), it was broken and was presented as two corrupted mail messages.
About a year ago, there was a thread on the list about the fact that Dovecot does not perform >From quoting when writing to mbox folders:
http://dovecot.org/list/dovecot/2004-October/004865.html
Timo, in that thread you mentioned the following about Dovecot's use of the content-length header:
On Tue, Oct 05, 2004 at 05:13:36PM +0300, Timo Sirainen wrote:
Dovecot (and eg. mutt) uses Content-Length header to figure out how large the message body is, so clients can't mess anything by sending From-lines. Also Dovecot requires that From-line has correct syntax and valid timestamp or it's not treated as From-line.
In the example above, the message *does* include a valid content-length header after it is initially written, but Dovecot seems to ignore the header when reading the folder, and it treats the "From " line in the body as a message separator. For example, a SELECT on the folder will return "2 EXISTS" even if the single message described above is the only message in the folder. I'm currently at CVS 20051104.
Glenn