On 1 July 2026, from 04:55Z to 20:10Z, IETF SMTP servers (25/tcp) were unreachable over IPv4. For these 15 hours, messages addressed to lists or aliases at ietf.org, irtf.org, iab.org, and rfc-editor.org over IPv4 were not accepted.
All outbound email and all inbound email over IPv6 were unaffected. Most users do not need to take further action. Most mail servers will have queued messages sent during this window for longer than the duration of this incident and will have successfully retried to send messages that were not previously delivered. If you sent mail during the window and your mail server was configured to quit trying before the window closed, you should have received an error message. However, if you are concerned your mail may have been dropped please check and resend. The cause was a change to the network filtering for mail2 that introduced a latent bug which unintentionally removed access for inbound 25/tcp connections over IPv4 when later activated by a separate change. This error was only possible because of the lack of strong configuration controls on the existing mail system as built by a contractor no longer working for the IETF. To avoid this kind of outage in the future, we have added additional external service monitoring for the affected ports and added a step to confirm any changes to the traffic flows are expected during _any_ configuration change. We are very close to moving to a re-architected system, which has been several months in planning and building, that has strong controls on configuration and versioning built-in, so we don't expect this kind of issue to repeat. Sam Sargeant New Machine Futures _______________________________________________ IETF-Announce mailing list -- [email protected] To unsubscribe send an email to [email protected]
