This article applies to:
- Trustwave MailMarshal (SEG)
Problem:
- Can't send email to some domains
- SMTP error message similar to: 554 This server requires PTR for unauthenticated connections
Information:
This response indicates that your server does not have a PTR record. Having a valid PTR record is best practice for email servers.
Some email services enforce the policy of requiring a valid Reverse DNS lookup (PTR record) for any email server sending to their servers.
The PTR record does not have to match the HELO name used to send email.
Resolution:
To resolve this issue, configure a DNS PTR record for your SEG server. For help with this requirement, consult your domain registrar, service provider, or persons in charge of DNS service for your network.