[Exim] mail rejection on size depending on where mail origin…

Currently our internet facing severs reject as early as possible (SMTP time
if possible) using the message_size_limit setting.

We have some internal servers which use a transport to detect large
messages and send mail to the sender since returning SMTP 5xx messages to
MUAs doesn't get handled very well IMHO.

I'm looking at possibly combining the 2 services on a single machine(s)
and while I could use the existing transport solution for all mail, I wondered
if there were better solutions out there? Does exim4 allow SMTP
rejection on size depending on IP address as well as allowing transports
which could do the same for another IP range? (I could use the exim3
transport until deployment of exim4....?)

Thanks

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Alan Thew
FAX: +44 151 794 4442