Re: [fetchmail-users] RETR with UIDL

[Matthias A. <mat...@gm...>]

Sunil Shetye <sh...@bo...> writes:

> Quoting from Jakob Hirsch's mail on Thu, Mar 02, 2006:
>> The difference is simply that fetchmail (ab)uses TOP by default to
>> retrieve mail, while usual MUAs use the standard mechanism of RETR.
>> Nevertheless, Comcast's POP3 server is plain broken if he allows TOP but
>> truncates messages with it.
>
> There is one case where fetchmail could use RETR instead of TOP. That
> is when "uidl" has been enabled.

Not in 6.3.X, as that would change semantics WRT other clients. The
assumption fetchmail makes is that "TOP" leaves seen flags (where
recorded in headers) and the "LAST" pointer (way obsolete) alone. Plus,
some b0rked servers apparently remove messages right after RETR (see
below).

Changing UIDL to imply "use RETR" is an option only for later versions,
although it looks sensible in itself -- compatibility matters here.

I don't like fetchmail's assumptions about undocumented behavior either
(which got us into this trouble), and it appears the price for not using
RETR is high, but changes like these are definitely 6.4.X stuff.

> fetchmail currently uses TOP. If the server is supporting "uidl", then
> it should not matter if fetchmail uses TOP or RETR as all the email
> clients

This is the thinko. Not all clients use UIDL.
Some (including fetchmail) still use LAST...

> Any votes for or against this?

Against.

The TODO in SVN's trunk directory already mentions:

| clean up TOP vs. RETR but leave TOP as an option for the server scum
| that deletes message right after RETR, voiding client retries (Jakob
| Hirsch, 2006-01-03).

-- 
Matthias Andree