[Dovecot] TAB characters in subject header continuation/wrap lines

[Stephen Warren]

I have some emails where the Subject line has been wrapped, and
subsequent lines are indented with TAB characters. Specifically, here's
a dump of a portion of an email:

0002020   C   c   :  sp  nl   S   u   b   j   e   c   t   :  sp   [   B
0002040   u   i   l   d   b   o   t   ]  sp   B   u   i   l   d   B   o
0002060   t  sp   S   U   C   C   E   S   S  nl  ht   (   B   l   d   _
0002100   g   s   s   d   k   _   g   s   s   d   k   _   t   e   s   t
0002120   _   2   0   0   6   _   0   9   _   1   2   _   0   0   _   0
0002140   1   _   0   0   _   I   n   c   r   e   m   e   n   t   a   l
0002160   _   2   )  nl   X   -   B   e   e   n   T   h   e   r   e   :

Note the HT about half way through the third line.

When I view this email using Thunderbird 1.5.0.5 on Windows XP, with
Dovecot 1.0.rc7 running on CentOS 4.3, this TAB character shows up as a
funny character in the subject line, as displayed by the Thunderbird.

My question is: Should Dovecot be detecting mail header continuation
lines that start with a TAB, and stripping the TAB (converting to a
space)? I *think* that's what the RFCs implied when I read up on this a
few months ago, but I may easily be mis-remembering.

A second somewhat off-topic question: When the automated system that
sends out these messages sends them to me directly, this problem does
not occur, because the email titles are not wrapped. However, when I
receive these emails via a mailman mailing list, mailman prepends the
text "[Buildbot]" on the front of the title, thus making the title long
enough to require wrapping. As such, I imagine that it's mailman that is
indenting the Subject continuation line with the TAB character. Is there
an issue in mailman - should mailman be indenting with e.g. a SPACE
character, or is mailman's action perfectly legal?

Thanks for any pointers.

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