On Wed 30 May 2018 at 20:58:12 -0400, Michael Stone wrote: > On Wed, May 30, 2018 at 06:22:49PM -0500, David Wright wrote: > > AIUI 587 is the standard email submission port and 465 is now > > deprecated but often still in use. I think they differ in the > > details of how they handle encrypting the session. > > > From a protocol standpoint 587/tcp is identical to 25/tcp, with the > distinction that it is designated for a end-users to submit messages for > delivery rather than accepting mail for delivery from external mail relays. > The expectation is that there is authentication of the submission, either > via allowed IPs, SMTP AUTH, or some other mechanism. Networks can block > port 25 to reduce spam originating from the network, but allow 587 for > visitors to submit email to their provider for delivery. Encryption is > activated with STARTTLS.
TLS is not offered by suddenlink.net on port 587: brian@stretch:~# nc smtp.suddenlink.net 587 220 omta01.suddenlink.net ESMTP server (InterMail vM.8.04.03.22 201-2389-100-167-20150619) ready Fri, 1 Jun 2018 06:45:17 -0500 ehlo test 250-omta01.suddenlink.net 250-HELP 250-XREMOTEQUEUE 250-ETRN 250-AUTH=LOGIN PLAIN 250-AUTH LOGIN PLAIN 250-PIPELINING 250-DSN 250-8BITMIME 250 SIZE 52428800 Exim will have to use "AUTH_CLIENT_ALLOW_NOTLS_PASSWORDS = true". -- Brian.