Re: [exim] How to reject overlong addresses/local parts in F…

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Author: Frank Richter
Date:  
To: exim-users
New-Topics: Re: [exim] How to reject overlong addresses/local parts in From: header?
Subject: Re: [exim] How to reject overlong addresses/local parts in From: header?

>
> On 12/12/2020 15:30, Jeremy Harris via Exim-users wrote:
>> On 12/12/2020 14:46, Frank Richter via Exim-users wrote:
>>> It comes from an e-mail with an overlong From: header:
>>> From: "…"
>>> <PPPPPPPPPPPPPPKKKKKKKKKKKKKKKKKTTTTTTTTTTTTTTTTTTTTTTTTRRRRRRRRRRRRRRRRRRRRRRRRSSSSSSSSSSSSSSSSSSSSSSSSSSAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAADDDDDDDDDDDDDDDDDFFFFFFFFFFFFFFFFFFFFFCCCCCCCCCCCCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB@…>
>>>
>>> I'd like to reject such "address monsters". How's the best way to
>>> achieve this?
>>
>> Try a rewrite rule:
>>
>> ^.{40,}@tuced.eu          deny_me@???
>>
>> before your existing rule.  Then a simple match-and-deny in your data ACL:
>>
>>   deny condition = ${if eq {deny_me@???} {${address:$h_from:}}}


Thanks.

This works for local parts from 40 up to 254 characters. For longer local
parts we get the same paniclog:
no @ found in the subject of an address list match …

So this isn't the proper solution yet.

These long addresses also comes an envelope-from now. This should be done in
an earlier ACL (acl_smtp_mail, acl_smtp_rcpt), not tested yet.

Frank

--
Frank Richter
URZ, Chemnitz University of Technology, Germany