On 12/12/2017 10:29 AM, Alex wrote: > Hi, > > We have postfix-3.1.4 set up on fedora25 to use submission for > outbound mail. How can I control the number of recipients that can be > addressed in any one email? > > Below is my submission config from master.cf. Perhaps it would just be > setting smtpd_recipient_limit specifically for submission? > > submission inet n - n - - smtpd > -o smtpd_tls_security_level=encrypt > -o smtpd_sasl_auth_enable=yes > -o smtpd_client_restrictions=permit_sasl_authenticated,reject > -o milter_macro_daemon_name=ORIGINATING > -o receive_override_options=$submission_overrides > -o syslog_name=postfix/submission >
Yes, you could add -o smtpd_recipient_limit to the submission service. HOWEVER, this feature isn't intended to limit abuse. Postfix will accept recipients up to $smtpd_recipient_limit and then temp-fail excess recipients. This will likely cause desktop software to give a confusing message, which might be sufficient for your purpose. A real MTA will disconnect and retry the excess recipients, possibly after a delay. > On a related question, how can we limit the number of recipients > addressed in any one inbound email? What does the sender receive when > that limit is reached? Will this cause problems with legitimate mail? > > The problem we're trying to solve is primarily disgruntled employees > retaliating via email and sending business-related information to all > employees. Obviously this is not a perfect solution, but one we hope > will deter the most egregious offenders. We also can't really restrict > it via our spam measures because the body contents are directly > business related. Of course we'd also like any of the anti-spam abuse > protections from this as well. If your intention is to reject mail with excess recipients, use a policy service in smtpd_data_restrictions. The policy service has a recipient_count attribute. http://www.postfix.org/SMTPD_POLICY_README.html http://postfwd.org/ -- Noel Jones
