todo.html - fetchmail in fetchmail

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<h1 class="c1">Fetchmail Bugs and To-Do Items</h1>

<p>Note that there is a separate <a href="TODO.txt">TODO.txt</a> document of
different content than this.</p>

<p>I try to respond to urgent bug reports in a timely way. But
fetchmail is now pretty mature and I have many other projects, so I
don't personally chase obscure or marginal problems. Help with any
of these will be cheerfully accepted.</p>

<h2>Serious</h2>

<p>Let IMAP code use UID and UIDVALIDITY rather than relying on flags
that everyone can alter.</p>

<h2>Normal</h2>

<p>POP3 hang when polling mail with NUL char that is rejected (David
Greaves) <a
	href="https://lists.berlios.de/pipermail/fetchmail-devel/2004-October/000154.html">https://lists.berlios.de/pipermail/fetchmail-devel/2004-October/000154.html</a></p>

<p>It has been reported that multidrop name matching fails when the
name to be matched contains a Latin-1 umlaut. Dollars to doughnuts
this is some kind of character sign-extension problem. Trouble is,
it's very likely in the BIND libraries. Someone should go in with a
debugger and check this.</p>

<p>The <a
href="http://bugs.debian.org/cgi-bin/pkgreport.cgi?pkg=fetchmail&amp;archive=no">
Debian bug-tracking page for fetchmail</a> lists other bug
reports.</p>

<h2>Cosmetic</h2>

<p>Alan Munday suggests message change MULTIDROP without ENVELOPE:</p>
<pre>
fetchmail: warning: MULTIDROP configuration for pop.example.org requires the envelope option to be set!
fetchmail: warning: Check ENVELOPE option if fetchmail sends all mail to postmaster!
</pre>

<h2>Feature requests/Wishlist items</h2>

<p>Feature request from "Ralf G. R. Bergs" &lt;rabe@RWTH-Aachen.DE&gt; "When
fetchmail downloads mail and Exim+SpamAssassin detecs an incoming
message as spam, fetchmail tries to bounce it. Unfortunately it uses
an incorrect hostname as part of the sender address (I've an internal
LAN with private hostnames, plus an official IP address and hostname,
and fetchmail picks the internal name of my host.) So I'd like to have
a config statement that allows me to explicitly set a senderaddress
for bounce messages."</p>

<p>In the SSL support, add authentication of Certifying Authority
(Is this a Certifying Authority we recognize?).</p>

<p>Laszlo Vecsey writes: "I believe qmail uses a technique of
writing temporary files to nfs, and then moving them into place to
ensure that they're written. Actually a hardlink is made to the
temporary file and the destination name in a new directory, then
the first one is unlinked. Maybe a combination of this will help
with the fetchmail lock file."</p>

<p>Maybe refuse multidrop configuration unless "envelope" is _explicitly_
configured (and tell the user he needs to configure the envelope
option) and change the envelope default to nil.  This would
prevent a significant class of shoot-self-in-foot problems.</p>

<p>Given the above change, perhaps treat a delivery as "temporarily
failed" (leaving the message on the server, not putting it into
.fetchids) when the header listed in the "envelope" option is not
found.  (This is so you don't lose mail if you configure the wrong
envelope header.)</p>

<p>Matthias Andree writes:</p>

<blockquote> 
<p>NOTE that the current code need optimization, if I have
unseen articles 3 and 47, fetchmail will happily request LIST for
articles 3...47 rather than just 3 and 47. In cases where the message
numbers are far apart, this involves considerable overhead - which
could be alleviated by pipelining the list commands, which needs
either asynchronous reading while sending the commands, or knowing the
send buffer, to avoid deadlocks. Unfortunately, I don't have the time
to delve deeper into the code and look around.</p>

<p>Note that such a pipelining function would be of universal use, so it
should not be in pop3.c or something. I'd think the best approach is to
call a "sender" function with the command and a callback, and the sender
will call the receiver when the send buffer is full and call the
callback function for each reply received.</p> 

<p>See the ESMTP PIPELINING RFC for details on the deadlock avoidance
requirements.</p>
</blockquote>

<hr />
<br clear="left" />
<address>-2003 Eric S. Raymond <a
	href="mailto:esr@thyrsus.com">&lt;esr@thyrsus.com&gt;</a><br />
2004- Matthias Andree <a
		href="mailto:matthias.andree@gmx.de">&lt;matthias.andree@gmx.de&gt;</a></address>
</body>
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1	<?xml version="1.0" encoding="ISO-8859-1"?>
2	<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
3	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
4	<html xmlns="http://www.w3.org/1999/xhtml">
5	<head>
6	<link rev="made" href="mailto:esr@snark.thyrsus.com" />
7	<meta name="description"
8	content="Known bugs and to-do items in fetchmail" />
9	<meta name="keywords" content="fetchmail, POP3, IMAP, bugs" />
10	<title>Fetchmail Bugs and To-Do Items</title>
11	<style type="text/css">
12	/<![CDATA[/
13	h1.c1 {text-align: center}
14	/]]>/
15	</style>
16	</head>
17	<body>
18	<h1 class="c1">Fetchmail Bugs and To-Do Items</h1>
19
20	<p>Note that there is a separate <a href="TODO.txt">TODO.txt</a> document of
21	different content than this.</p>
22
23	<p>I try to respond to urgent bug reports in a timely way. But
24	fetchmail is now pretty mature and I have many other projects, so I
25	don't personally chase obscure or marginal problems. Help with any
26	of these will be cheerfully accepted.</p>
27
28	<h2>Serious</h2>
29
30	<p>Let IMAP code use UID and UIDVALIDITY rather than relying on flags
31	that everyone can alter.</p>
32
33	<h2>Normal</h2>
34
35	<p>POP3 hang when polling mail with NUL char that is rejected (David
36	Greaves) <a
37	href="https://lists.berlios.de/pipermail/fetchmail-devel/2004-October/000154.html">https://lists.berlios.de/pipermail/fetchmail-devel/2004-October/000154.html</a></p>
38
39	<p>It has been reported that multidrop name matching fails when the
40	name to be matched contains a Latin-1 umlaut. Dollars to doughnuts
41	this is some kind of character sign-extension problem. Trouble is,
42	it's very likely in the BIND libraries. Someone should go in with a
43	debugger and check this.</p>
44
45	<p>The <a
46	href="http://bugs.debian.org/cgi-bin/pkgreport.cgi?pkg=fetchmail&archive=no">
47	Debian bug-tracking page for fetchmail</a> lists other bug
48	reports.</p>
49
50	<h2>Cosmetic</h2>
51
52	<p>Alan Munday suggests message change MULTIDROP without ENVELOPE:</p>
53	<pre>
54	fetchmail: warning: MULTIDROP configuration for pop.example.org requires the envelope option to be set!
55	fetchmail: warning: Check ENVELOPE option if fetchmail sends all mail to postmaster!
56	</pre>
57
58	<h2>Feature requests/Wishlist items</h2>
59
60	<p>Feature request from "Ralf G. R. Bergs" <rabe@RWTH-Aachen.DE> "When
61	fetchmail downloads mail and Exim+SpamAssassin detecs an incoming
62	message as spam, fetchmail tries to bounce it. Unfortunately it uses
63	an incorrect hostname as part of the sender address (I've an internal
64	LAN with private hostnames, plus an official IP address and hostname,
65	and fetchmail picks the internal name of my host.) So I'd like to have
66	a config statement that allows me to explicitly set a senderaddress
67	for bounce messages."</p>
68
69	<p>In the SSL support, add authentication of Certifying Authority
70	(Is this a Certifying Authority we recognize?).</p>
71
72	<p>Laszlo Vecsey writes: "I believe qmail uses a technique of
73	writing temporary files to nfs, and then moving them into place to
74	ensure that they're written. Actually a hardlink is made to the
75	temporary file and the destination name in a new directory, then
76	the first one is unlinked. Maybe a combination of this will help
77	with the fetchmail lock file."</p>
78
79	<p>Maybe refuse multidrop configuration unless "envelope" is _explicitly_
80	configured (and tell the user he needs to configure the envelope
81	option) and change the envelope default to nil. This would
82	prevent a significant class of shoot-self-in-foot problems.</p>
83
84	<p>Given the above change, perhaps treat a delivery as "temporarily
85	failed" (leaving the message on the server, not putting it into
86	.fetchids) when the header listed in the "envelope" option is not
87	found. (This is so you don't lose mail if you configure the wrong
88	envelope header.)</p>
89
90	<p>Matthias Andree writes:</p>
91
92	<blockquote>
93	<p>NOTE that the current code need optimization, if I have
94	unseen articles 3 and 47, fetchmail will happily request LIST for
95	articles 3...47 rather than just 3 and 47. In cases where the message
96	numbers are far apart, this involves considerable overhead - which
97	could be alleviated by pipelining the list commands, which needs
98	either asynchronous reading while sending the commands, or knowing the
99	send buffer, to avoid deadlocks. Unfortunately, I don't have the time
100	to delve deeper into the code and look around.</p>
101
102	<p>Note that such a pipelining function would be of universal use, so it
103	should not be in pop3.c or something. I'd think the best approach is to
104	call a "sender" function with the command and a callback, and the sender
105	will call the receiver when the send buffer is full and call the
106	callback function for each reply received.</p>
107
108	<p>See the ESMTP PIPELINING RFC for details on the deadlock avoidance
109	requirements.</p>
110	</blockquote>
111
112	<hr />
113	<br clear="left" />
114	<address>-2003 Eric S. Raymond <a
115	href="mailto:esr@thyrsus.com"><esr@thyrsus.com></a><br />
116	2004- Matthias Andree <a
117	href="mailto:matthias.andree@gmx.de"><matthias.andree@gmx.de></a></address>
118	</body>
119	</html>

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