OT: SMTP (was Re: OT: noreply at ......)

[Kenneth Brody]

On 7/2/2013 1:25 AM, Bill Campbell wrote:
> On Mon, Jul 01, 2013, Kenneth Brody wrote:
[...]
>> The "from" part of e-mails has never been reliable.  All it says is what the
>> sender wants it to say.  (Over the years, I've convinced people who refused
>> to believe that by sending them an e-mail "from" <president at whitehouse.gov>.)
[...]
> Remember the SMTP email protocol is an abbreviation of Simple
> Mail Transport Protocol with emphasis on Simple.  It was designed
> in a era when the network consisted mostly of reasonably
> trustworth folks, universities, engineers, and other tech savvy
> types who wouldn't think of abusing other people's servers.

The same can be said about many of the long-standing Internet protocols. 
(Anyone else remember "anonymous FTP" with the "please enter your e-mail 
address as the password"?)

[...]
> Many broadband providers restrict their residential customer's
> ability to send outbound SMTP on port 25 to any mail servers
> other than the provider's.  They also restrict outgoing messages
> through their servers to those with From: addresses in their own
> domains.  Both these conditions cause issues with people who may
> want to run their own mail servers on Linux or other *nix
> systems.  When our customers with this type of problem, we
> usually set up their systems to send outgoing mail through one of
> our servers using a different port, usually using SMTP AUTH to
> prevent spoofing.

Verizon restricts outgoing port 25 to their own SMTP servers, which also 
require some sort of AUTH.  (Actually, I just checked, and my outgoing 
"ESMTP" configuration is set to use Verizon's servers on port 587.  A quick 
check of their FAQ confirms that they started blocking port 25 entirely 
several years ago for all dynamic IP customers.)  Fortunately, I can use any 
"from" I want, so I can do things such as use my fptech.com address for 
"official" fPTech e-mails.  They also don't block SMTP from other ports, so 
I can use other servers, such as gmail, when needed.

-- 
Kenneth Brody