Re: [exim] EHLO loop

Christian Gregoire, 2010-03-19 11:26:

> One of my clients' MTA is going mad from time to time, issuing 'EHLO
> <name>' command in a never-ending loop. Exim politely answers with
> the SMTP banner and the extensions available.
>
> Is there an option equivalent to smtp_accept_max_per_connection to
> limit the number of EHLO/HELO commands in a single SMTP connection ?

No, but as with most things, you can build that yourself. Put something
like that in your acl_check_helo:

deny
set acl_c_helo_count = ${eval10:0$acl_c_helo_count+1}
condition = ${if > {$acl_c_helo_count}{2}}
message = Too many HELO/EHLOs

Note that this allows 3 HELOs and you should probably not increase it,
as clients will re-issue a HELO after STARTTLS and the counter is not reset.
Feel free to limit this to your internal network with "hosts =
so.me.net.work/mask", slow down the client with "sleep" or use "drop"
instead of "deny".