[exim] Re: Excessive "bad recipient" messages in syslog

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Author: Jarland Donnell via Exim-users
Date:  
To: exim-users
Subject: [exim] Re: Excessive "bad recipient" messages in syslog


I've been following this particular botnet pretty closely. It's an
incredible one. If anyone is interested, I have a list of IPs of this
botnet that increase daily:
https://github.com/mxroute/da_server_updates/blob/master/sec/botnet.list

It's been a good while since I've seen a botnet this persistent and slow
to reveal itself. Usually one of this size blows it's wad all in one go
and you can list out every currently infected PC/IP in a day or so. This
one seems to either be taking it's time, or is adding new systems to
it's list at a very solid pace.

On 2023-05-28 16:09, Jim Fenton via Exim-users wrote:

> It seems like some of the spammers have changed tactics and are now
> sending messages with 98 or so bad RCPT addresses, which (happily) Exim
> detects. But now I'm getting a flood of messages in syslog, such as:
>
> 2023-05-28 00:24:39 REJECT [168.121.195.104]: bad recipient count high
> [9]
> 2023-05-28 00:24:39 H=([168.121.195.104]) [168.121.195.104]
> F=<70g3gpds9l3n8@???>
> rejected RCPT <comercial@???>: Rejected for too many bad
> recipients
>
> …many lines deleted…
>
> 2023-05-28 00:24:39 REJECT [168.121.195.104]: bad recipient count high
> [98]
> 2023-05-28 00:24:39 H=([168.121.195.104]) [168.121.195.104]
> F=<70g3gpds9l3n8@???> rejected RCPT <admin@???>:
> Rejected for too many bad recipients
>
> I can easily change the configuration to make this happen silently, but
> I would like some visibility that this is happening, for example, in my
> daily logwatch output. Has anyone devised a way to cut down on the
> number of messages without eliminating them entirely?
>
> -Jim


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