ISP filtering port 25

Lennart Sorensen lsorense-1wCw9BSqJbv44Nm34jS7GywD8/FfD2ys at
Mon Mar 17 16:32:27 UTC 2014

On Mon, Mar 17, 2014 at 04:26:26PM +0000, Ben Walton wrote:
> No, that's not what I'm saying. Change "not allowed to" to shouldn't.
> Anyone capable of running a mail server properly doesn't need port 25
> egress and those that aren't capable shouldn't. I'd argue that lists
> like
> are very useful. Again, if you're clued in, you're perfectly able to
> relay mail out using TLS and authentication. If not...well, you
> probably shouldn't be sending the mail out.

You would have to find someone (maybe your ISP) willing to do relaying
for your domain (I suppose if you are authenticating as a valid user of
the ISP, they should, given the mail can at least trace who is responsible
for the email).

> ISP's are doing the internet in general a favour by blocking this
> port. It provides such an incredibly low signal to noise ratio that
> blocking it to prevent spambots is the right choice. (ISP's blocking
> _inbound_ tcp/25 is a different matter.)
> That's not to say it's without is unfortunate and I'd prefer
> a network where this isn't required. That said, I'm a realist and the
> genie is out of the bottle.

Well at least teksavvy as far as I know will let you run with port
25 unblocked if you have a static IP although you may have to ask to
be unblocked.

I don't run a mail server myself.  Sometimes I think I should, but it
seems like work. :)

Len Sorensen
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