Outgoing SMTP Servers

Bill Stewart nonobvious at gmail.com
Thu Nov 3 21:15:19 UTC 2011


On Mon, Oct 31, 2011 at 6:23 AM, Brian Johnson <bjohnson at drtel.com> wrote:
> For clarity it's really bad for ISPs to block ports other than 25 for the purposes of mail flow control... correct?
Yes, correct.  If you're using another mail submission port, you're
connecting to a mail service that has the responsibility not to let
spam escape, and your ISP has done its job of stopping point-source
pollution.


>Bill>I've got a strong preference for ISPs to run a
>Bill>Block-25-by-default/Enable-when-asked.  [...]

> This is, of course, exactly why this blocking is done.

It looks like you're missing half my point, which is the Enable-when-asked part.
There are users who are perfectly legitimately running MTAs at home,
whether for reliability or privacy (e.g. so they can run SMTP-over-TLS
end-to-end) or just simplicity, and ISPs shouldn't be blocking them
(unless they're spammers, of course.)

> My take on this is that it IS best practice to have users use the submission port (587) for mail submission from the MUA to an MTA.
If you're running an MTA service, then yes.  If you're running a
transport service, then not necessarily.


-- 
----
             Thanks;     Bill

Note that this isn't my regular email account - It's still experimental so far.
And Google probably logs and indexes everything you send it.




More information about the NANOG mailing list