On 11/07/14 15:35, Jeremy Visser wrote: > On 11/07/14 14:27, Stephen Rothwell wrote: >> Well, if for no other reason than that many ISPs insist that you use >> their mail server for outgoing email > Who does this? I would invite you to name-and-shame them. > > But before you do so, check that you are sending outbound as port 587 > (STARTTLS) or 465 (TLS). It's common for providers to block port 25 due to > rampant abuse, but as all port 587 or 465 based services are authenticated > relays, there is no need to block this. > > I know of some ISPs (e.g. Telstra 3G) who block port 25, but that's not the > end of the world given that ports 465 and 587 are meant to be used these days > for SMTP submission anyway. > > (Blocking port 25 on Telstra 3G makes sense because it is a giant CGNAT > network. Think about it this way -- if they _allowed_ port 25, the CGNAT > pool would constantly be listed/delisted from blacklists which would affect > hundreds of customers at once.) > > As a network/systems admin at a small ISP, I personally hate running mail > services. I prefer layers 2-3...layer 7 can get stuffed. :-) While I > provide an anonymous SMTP relay for customers who for some goddamn stupid > reason insist on using one, I do nothing to encourage people to use it, and > usually try to talk people out of it. > Why anonymous - can't you require them to STARTTLS+AUTH, even on port 25?
Optus blocks port 25 outbound too. Shrug; the customer IPs are listed in the dynamic IP blacklists anyway from memory. They don't block 465 or 587 though. Hamish _______________________________________________ Link mailing list Link@mailman.anu.edu.au http://mailman.anu.edu.au/mailman/listinfo/link
