I don't see this in my home market, but I do see it in someone else's... I kind of expect this for port 25 but... J@mb-aye:~$telnet 147.28.0.81 587 Trying 147.28.0.81... Connected to nagasaki.bogus.com. Escape character is '^]'. 220 nagasaki.bogus.com ESMTP Sendmail 8.14.9/8.14.9; Thu, 27 Nov 2014 19:17:44 GMT ehlo bogus.com 250-nagasaki.bogus.com Hello XXXXXXXXXXXXXXX.wa.comcast.net [XXX.XXX.XXX.XXX], pleased to meet you 250 ENHANCEDSTATUSCODES J@mb-aye:~$telnet 2001:418:1::81 587 Trying 2001:418:1::81... Connected to nagasaki.bogus.com. Escape character is '^]'. 220 nagasaki.bogus.com ESMTP Sendmail 8.14.9/8.14.9; Thu, 27 Nov 2014 19:18:33 GMT ehlo bogus.com 250-nagasaki.bogus.com Hello [IPv6:2601:7:2380:XXXX:XXXX:XXXX:c1ae:7d73], pleased to meet you 250-ENHANCEDSTATUSCODES 250-PIPELINING 250-8BITMIME 250-SIZE 250-DSN 250-AUTH DIGEST-MD5 CRAM-MD5 LOGIN 250-STARTTLS 250-DELIVERBY 250 HELP that's essentially a downgrade attack on my ability to use encryption which seems to be in pretty poor taste frankly.