6. Explanations of our error messages

Here is a list of error messages given by the University mail relay service.

When the term HELO is used it should also be taken to include EHLO.

Words beginning with $ are variables which are substituted with applicable values in each message.

6.1. DAT-CLM: Message contains malware ($malware_name)

Explanation

Message contains malware. The name Oversized.Foo means that an archive of format Foo had too high a compression ratio (currently limited to 300:1).

Solution

Remove the malware. For Oversized.Foo you can try one of the following
  • Reduce the compression ratio to below 300:1
  • Encrypt the archive to prevent unpacking
  • Use a protocol designed for file transfer (SMTP wasn't)

6.2. HLO-FOR: Forged HELO

Explanation

The sending MTA is forging the HELO command by using another host's identity.

Solution

The sending MTA must use its own identity.

6.3. HLO-INT: Oxford host claiming non-Oxford identity

Explanation

An Oxford host is claiming an identity with the HELO command that is not in the ox.ac.uk domain. All Oxford IP addresses must be registered in ox.ac.uk .

Solution

Use a HELO argument in the ox.ac.uk domain.

If you are unable to configure your mail server correctly then you should smarthost to smtp.ox.ac.uk instead which does not impose this condition.

6.4. HLO-MIS: No HELO before mail transaction

Explanation

The mail transaction was started without first using the HELO command. See RFC5321 section 4.1.4.

Solution

Use the HELO command before starting the mail transaction.

6.5. HLO-SYN: HELO is syntactically invalid

Explanation

The HELO command does not meet basic syntax standards. Read RFC1123 section 5.2.5 and RFC5321 section 4.1.1.1 for the rules of choosing the HELO argument.

Solution

Use a valid HELO. If your mail server is called foo.example.com then issue the command HELO foo.example.com .

6.6. HLO-UND: HELO contains invalid underscore character

Explanation

The HELO argument contains an underscore. The underscore character (_) is not a member of the SMTP character set. A common mistake is for MS Windows administrators to use the host's NetBIOS name containing an underscore.

Solution

Use a HELO argument without an underscore.

6.7. HST-BAN: Sending host blacklisted

Explanation

The sending host is blacklisted.

Solution

Contact us for details.

6.8. HST-PTR: Oxford host has no PTR record

Explanation

The Oxford sending host has no PTR record in the DNS. This is a contravention of ICTC Regulations.

Solution

Contact your local IT staff and get your host registered.

6.9. RLY-OPN: Open relay not permitted

Explanation

You are attempting to use our MTA as an open relay.

Solution

Use the MTA appropriate for your IP address or the recipient domain.

6.10. RPT-ALU: Recipient unknown

Explanation

The recipient is unknown at Oxford.

Solution

Check that you are using the correct address. Search for alumni email addresses on the Oxford Alumni Email website (members only).

6.11. RPT-BAN: Recipient blacklisted

Explanation

The recipient is blacklisted.

Solution

Contact us for details.

6.12. RPT-CAL: Callout verification failed

Explanation

The downstream MTA will not accept the recipient address. Any error message given by that MTA is included in our error message.

Solution

Check with the recipient as to his/her correct address.

6.13. RPT-CHR: Recipient local-part contains a banned character

Explanation

The recipient local-part contains one of of the following banned characters @ ! % / | "

Solution

Use a recipient local-part without a banned character.

6.14. RPT-OBS: Recipient domain is obsolete

Explanation

The recipient domain is no longer in use.

Solution

Use the suggested new address or our contact search pages

6.15. RPT-UNK: Recipient unknown.

Explanation

The recipient is unknown at Oxford.

Solution

Check that you are using the correct address. Search for email addresses on our contact search pages.

6.16. SND-BAN: Sender address blacklisted

Explanation

The sender address is blacklisted.

Solution

Contact us for details.

6.17. SND-VFY: Sender domain verification failed

Explanation

The sender domain is not correctly registered in the DNS.

Solution

Make sure that the sender domain is correctly registered in the DNS and that the authoritative DNS servers are accessible.

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