Author: Felix Schwarz Date: To: exim-users Subject: Re: [exim] Prevent / refuse Mail from : <> null sender in exim
Am 08.11.2016 um 08:50 schrieb Mueller: > we have a problem with null sender mails. The mails getting started with
> spams comming in, and just result in relay access denied:
>
> Message 1c2Zcm-0007Qi-L7 has been frozen (message created with -f <>).
> The sender is <>.
>
> The following address(es) have yet to be delivered:
> schulzanne@??? <schulzanne@???>: SMTP error from remote mail
> server after RCPT TO:<schulzanne@???>: host mail.tropenklinik.de
> [213.185.88.41]: 554 5.7.1 <schulzanne@???>: Relay access denied
Maybe it's just that I had too little morning coffee but I'm not sure I
understand your problem:
1. You get messages with from the '<>' sender, mostly spam.
2. Why do you try to send (these?) messages to hotmail?
Basically in a correctly configured mail system you should not see many frozen
messages.
Is the problem that some spammer sent spam with your domain as return path so
you are getting all the bounces from other badly configured servers?
If so you might want to deploy the backscatterer DNSBL to reject <> messages
as a stop-gap measure.
Personally none of my clients had backscatter problems anymore since we
deployed SPF+DMARC so you might want to try that as well (but maybe we were
just lucky).
> How can I discard this messages or set up exim to refuse any null sender
> (senders= : )!?? So no one can send with , mail from :<>.
I would not recommend implementing this as a general rule (at most in
conjuction with a DNSBL like backscatterer).
