Mail from the IPv6 world?!
An excerpt from the mail server log:
Feb 6 13:40:27 beastie amavis[81393]: (81393-03) Passed CLEAN, [3ffe:401d:203a:41:a00:2bff:fe86:af46] bounces-tech-net-owner-delphij=frontfree.net@NetBSD.org -> delphij@frontfree.net, Message-ID: oqfz0aqmaz.fsf@castrovalva.Ivy.NET, Hits: -2.599, 15863 ms