North American Network Operators Group

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RE: Why do so few mail providers support Port 587?

  • From: Christopher X. Candreva
  • Date: Fri Feb 25 15:34:54 2005

On Fri, 25 Feb 2005 [email protected] wrote:

> being used on port 25 already.  You can do SMTP AUTH just as easily on
> port 25 without having to re-educate your users and still net the same
> simplified tracking procedures that you mention.  It sounds to me like
> what we should really be talking about is getting MTA operators to begin
> using SMTP authentication of some kind (any kind!), rather than harping
> on whether or not MTA's should accept mail on port 587...

Port 587 becomes useful because it allows you to firewall outbound port 25 
from non-mail servers (IE -users), while allowing them to submit mail to 
other places.

It's hard to say how it benefits YOU as a single person. But the separation 
benefits the Internet as a whole.

It's a two part thing though. Blocking port 25 won't work without and 
alternative for users, and having mail submitted to relays on 587 isn't 
helpful if local admins don't block port 25 outbound for their users.

However, with both of these in place, you stop the ability of every 
virus-infected host to send mail out directly to other people's mail 
servers. Forcing them through your mail relay gives you control: Your virus 
scanner can now detect the traffic, issue an alert, shut down the account, 

So to answer Nil's original question, along the lines of giving him a 
reason to listen on port  587, the only selfish reason would be so your 
users behind port 25 firewalls can relay through your server. If you don't 
need that, that don't bother. 

Simply making this available has caused us really no 
additional support requests, it's maybe two lines in the file.

On the other hand, Optimum Online deciding to block outbound port 25 
one (Saturday) morning caused quite a bit of support work. Had we not 
already been supporting 587 at that point, the work would have been far 
greater, if not for the techs, then for the salespeople trying to get new 
customers to replace all the ones we would have lost.

Chris Candreva  -- [email protected] -- (914) 967-7816
WestNet Internet Services of Westchester