5. Sending mail from outside Oxford

This section relates to sending mail from outside Oxford to oxmail in its mail exchanger role.

Mail to postmaster@ox.ac.uk and abuse@ox.ac.uk bypasses most checks in order to allow queries about problems.

DNS-based blacklists

The following DNSBLs are used

MAPS RBL+ rbl-plus.mail-abuse.ja.net http://www.mail-abuse.com/
PSBL psbl.surriel.com http://psbl.org/
Spamcop bl.spamcop.net http://spamcop.net/
Spamhaus ZEN zen.dnsbl.ja.net http://www.spamhaus.org/zen/

Mail coming from a server listed in one of these DNSBLs won't be rejected. It will attract a weighting in the SpamAssassin scoring and also experience small delays in response to some SMTP commands.


Mail transactions must start with HELO.

The HELO argument must be syntactically correct. See RFC1123 section 5.2.5 and RFC5321 section for guidance on choosing your HELO argument. A common mistake is to use the underscore character; this is not allowed.


The envelope sender must be valid and accept error messages (aka bounces). A common mistake is to send mail from a script without thinking about the sender address e.g. apache@foo.example.com . If there's neither an MX record for nor an MTA on foo.example.com then the sender address will be invalid.


No recipient local-part may contain any of the following characters @ ! % / | "

The maximum number of recipients allowed for one message is 500. Excess recipients are temporarily rejected.


The maximum message size is 100 Mbytes.

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