Bringing this back on list.
On 10 Jun 2011, at 17:04, Bill Hayles wrote:
> Hi, Ian
>
> On Fri, 10 Jun 2011 15:31:46 +0000 in message number <8B2D9219-B9E1-417C-91CB-7FFFE5F53EED@???>, received here on 10/06/2011 16:48:12, Ian Eiloart <iane@???> said:
>
>
>>
>> That's true, but when an ISP blocks outbound port 25, two advantages are gained:
>>
>> 1. The ISP can spot, and deal with customers who are sending spam.
>>
>> 2. If the ISP doesn't do that, then the recipients can deal with the ISP instead of the ISP's customers. That's easier because there are fewer people to deal with, and they should have better technical knowledge.
>
> And a couple of big disadvantages.
>
> (1) The ISP prohibits their customer from using any mail server other than
> their own (which is a very bad thing in my book)
No, they don't. SMTP submissions should be made on port 587, not port 25. Almost all users now have access to port 25. See RFCs 2476 (dated 1998, 4409, and 5068):
http://www.ietf.org/rfc/rfc5068.txt
Most modern email clients will now default to port 587, not port 25. The difference is that the server will usually require secure authentication.
> (2) The ISP prevents their customer from running any kind of mail server
> (which is why I use an ISP that explicitly allows it)
That's a real benefit, given that most mail servers are spambots. If you have a need to run your own mail server, then you should have special arrangements with your ISP. Responsible ISPs will close port 25 by default, and probably only open it for business account holders with specific requirements. It would be nice if the IP address owner could publish a sort of reverse SPF policy, saying which domains are permitted to use the IP address.
> Point 2 may be specialist, but point 1 certainly isn't.
>
>
>
>
> --
> This is Spain. We do things differently here!
>
> Bill Hayles
> billnot@???
>
--
Ian Eiloart
Postmaster, University of Sussex
+44 (0) 1273 87-3148
