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Re: [PLUG] Postfix address re-write rules?
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> Date: Mon, 1 Mar 2010 15:40:57 -0500
> From: "Claude M. Schrader" <plug@claudeschrader.com>
> Subject: Re: [PLUG] Postfix address re-write rules?
>
> On 15:32 Mon 01 Mar , JP Vossen wrote:
>> Fair warning: I haven't Googled this yet. I have a hunch I'll find a
>> bunch of stuff that is almost, but not quite, completely wrong for what
>> I'd like to do.
>>
>> Problem: there is an external email address to which I can send email
>> but my wife can't. This is due to an incredibly FUBAR remote mail
>> server, over which I have no control and which has not improved in
>> years, nor will it. Ever. :-( Note we're both using my server, on my
>> domain, mine works because of a special exception on the remote side
>> that we can't get duplicated. (Don't ask.)
>>
>> Work-around: when my wife replies to that address, she can manually
>> change it to a different one that works. Except sometimes she forgets,
>> and the broken server never send a failure message either so the reply
>> just vaporises.
>>
>> Proposed Solution: Ideally, if my wife sends an email to the bad address
>> (due to hitting reply and forgetting to change it), Postfix will
>> re-write with a good address, but if I send it will do nothing. Worst
>> case, I just re-write everything going to the bad address with the good one.
>>
>> IOW, ideally:
>> me --> bad.com = just works
>> wife --> bad.com --} postfix changes to good.com = works
>>
>>
>> Anyone have any clues? I'm using stock Lenny Postfix 2.5.5-1.1 if that
>> matters.
Obviously I should have mentioned that she's using stock Thunderbird on
Hardy. Tweaking at MUA didn't even occur to me, but would be perfect if
possible.
> Possible Solution 1: defriend that person. You must *really* like
> that person to deal with such a broken mailserver
It's the email server where my Mom works... What can I say? I've
reported all their problems in painful detail, with citations to the
RFC, several times over the years. Given the nature of her department,
this brokenness is a major problem for them, but no one has ever gotten
IT to do diddly about it. So I'm done, except for trying to kludge
around it.
As noted, right now, I can send to her at work, which is sometimes
useful, but my wife can't *and the message just vanishes with no
bounce*, so no one knows about the miss. That can cause scheduling and
other issues, but is actually pretty rare, so my wife doesn't want me to
spend too much time on it.
> Possible Solution 2: I'm not sure what MUA your wife uses, but I
> know with mutt you can set up hooks to automatically set the from
> address based some some arbitrary criteria. There may be a thunderbird
> extention to do the same?
Never even occurred to me, so thanks. I looked and didn't find
anything, which is certainly not definitive.
> Possible Solution 3: Also, look into the sender_canonical_maps config option in postfix. It can
> do some sort of outgoing sender address rewriting, but I have no idea how
> granular it is.
I found that in my Postfix book after I sent the OP. (Duh.) That or
maybe aliases actually looks really trivial to do, but they are
all-or-nothing.
> ------------------------------
> Date: Mon, 01 Mar 2010 18:43:44 -0500
> From: Richard Freeman <r-plug@thefreemanclan.net>
[...]
> I'm not sure if this will work or not, but have you considered:
>
> 1. Configure postfix to service mail for bad.com.
> 2. Use a mail alias or virtual address to handle the rewrite.
>
> Only issue I can see is that you're now an open relay for mail going to
> bad.com (for only those addresses defined in alias/virtual).
>
>
> ------------------------------
> Date: Tue, 2 Mar 2010 07:36:12 +0100
> From: sean finney <seanius@seanius.net>
>
> On Mon, Mar 01, 2010 at 06:43:44PM -0500, Richard Freeman wrote:
>> I'm not sure if this will work or not, but have you considered:
>>
>> 1. Configure postfix to service mail for bad.com.
>> 2. Use a mail alias or virtual address to handle the rewrite.
>
> you should be able to do (2) without needing to do (1).
Yup, I think either of those would work, though a simple alias (2) is
both easier and more secure than spoofing (1). But again, they are
all-or-nothing.
> it's possible that you could work around the problem with a custom
> virtual(5) map, but with the description being in such broad
> strokes, who knows :)
Interesting. Based on my reading of the man page, that looks like it's
for incoming mail for users without local machine accounts though. Did
I miss something?
I also thought about writing a custom "command based filter" using
Postfix pipes. Even though the logic is trivial (if ${sender} == Wife
&& ${recipient} == Mom_bad; then ${recipient} = Mom_good) the rest of
the moving parts look like more trouble, performance hit and loss of
robustness than this is worth.
http://www.postfix.org/FILTER_README.html
Then I thought about Postfix header checks. Redirect *looked* good, but
sounds like it would break with multiple recipients. Replace could fix
the address, but they all only work 1 line at a time, so again it's
all-or-nothing. :-( http://www.postfix.org/header_checks.5.html
Thanks for all the thoughts and feedback,
JP
----------------------------|:::======|-------------------------------
JP Vossen, CISSP |:::======| http://bashcookbook.com/
My Account, My Opinions |=========| http://www.jpsdomain.org/
----------------------------|=========|-------------------------------
"Microsoft Tax" = the additional hardware & yearly fees for the add-on
software required to protect Windows from its own poorly designed and
implemented self, while the overhead incidentally flattens Moore's Law.
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