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Visitor
tpc2881
Posts: 1
Registered: ‎09-10-2010

Outlook outgoing emails blocked on port 25

I use outlook as my email manager. When comcast moved away from port 25 i lost the ability to send out bound emails through my company's server for my business franchise. i can receive but can not send. It will just hang up in the outbox. When I contacted the company there help desk said they are not equipped to help with outlokk and i have to contact comcast to get an alternate port. Does this make sense and if so what configuration should i use?

Email Expert
CCCarole
Posts: 28,918
Registered: ‎05-21-2006

Re: Outlook outgoing emails blocked on port 25

The recommended settings can be found in this clickable link:  LINK



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Mac Expert
Joel
Posts: 5,829
Registered: ‎12-01-2003

Re: Outlook outgoing emails blocked on port 25

Your company's email server should be supporting authenticated send (it is an internet standard after all), especially since many ISPs are implementing Port 25 blocks. Port 25 does not require authentication, therefore it is easily compromised by spammers. Check with your IT dept. to see if they support Port 587 with plain text authentication over an encrypted connection, or port 465 with authentication and SSL encryption. If they do not support one of these alternative ports, your only option is to use Comcast's SMTP for outgoing mail until your company changes their policy.

Bronze Problem Solver
Posts: 3,280
Registered: ‎05-12-2006

Re: Outlook outgoing emails blocked on port 25

 


Joel wrote:

Your company's email server should be supporting authenticated send (it is an internet standard after all), especially since many ISPs are implementing Port 25 blocks. Port 25 does not require authentication, therefore it is easily compromised by spammers.

 

That's not quite the right slant on things. Comcast could require authentication when connecting to their outgoing servers on port 25 just by twiddling a knob or two. And, in any case, the outgoing Comcast servers are rate limited, so they're not very attractive to spammers. Yes, we've seen instances where accounts have been compromised and spammers have used webmail to send spam to the address book contacts, but that's not the norm, and it has nothing to do with port 25, anyway.


The reason port 25 gets blocked isn't because it's "easily compromised by spammers.", it's because it's the port that every MX server on the Internet "listens" on, and ISPs don't want their spambots to be able to send email to the outside at a rate that's limited only by the bandwidth that's available.

 

 

Regular Contributor
Posts: 44
Registered: ‎10-05-2003

Re: Outlook outgoing emails blocked on port 25

I'm incensed by this arbitrary change on Comcast's part, with no regard to the consequences for end-users.

 

There should at worst be an "opt out" program for those people that need unblocked port 25 which could be accompanied with a warning about SPAM, etc.

 

I guess it's time to start looking for another service provider for home and business.

Bronze Problem Solver
Posts: 3,280
Registered: ‎05-12-2006

Re: Outlook outgoing emails blocked on port 25

 


Anon154847 wrote:

I'm incensed by this arbitrary change on Comcast's part, with no regard to the consequences for end-users.

 

There should at worst be an "opt out" program for those people that need unblocked port 25 which could be accompanied with a warning about SPAM, etc.

 

I guess it's time to start looking for another service provider for home and business.


Look before you leap. Most "home" ISPs block outgoing port 25. Comcast is kind of an odd duck in that outgoing port 25 being unblocked is the default state.

 

Regular Contributor
Posts: 44
Registered: ‎10-05-2003

Re: Outlook outgoing emails blocked on port 25

That's irrelevant and facetious.

 

Comcast arbitrarily took action without regard to the consequences of their end users.

 

Not "ALL" ISP's block 25, they often permit port 25 usage, but block inbound 25 connections to their own servers.

 

There are home monitoring systems that send alerts via port 25 e-mail messages ( I have one ) as well as a slew of other alerting devices and software that Comcast has rendered useless.

 
Comcast could have put up an "opt out" web page or program with a few hoops to jump through to discourage most casual users. That followed with a warning about potential problems with Port 25 and the termination of support for port 25 from their own servers, would take care of 99.9% of the complaints and issues they have.
  
As it is, port 25 blocking is just another Draconian move.

 

Email Expert
Posts: 18,241
Registered: ‎04-27-2004

Re: Outlook outgoing emails blocked on port 25

Port 25 is considered obsolete for email submission, the recommend port has been 587 for at least a decade. Port 25 is for server-to-server transmission.

 

If you have equipment that insists on using it, you should complain to the vendor. They should allow port 587 and authentication.

 

And Steve is correct that many ISPs block port 25 entirely from customer connections.

Bronze Problem Solver
Posts: 3,280
Registered: ‎05-12-2006

Re: Outlook outgoing emails blocked on port 25

 


Barmar wrote:

 

And Steve is correct that many ISPs block port 25 entirely from customer connections.


That's not what I said, and I don't think that's true. I think that most "home" ISPs block *outgoing* port 25, but allow users to reach the ISP's SMTP servers on port 25. Which would be fine for the "notification" scenarios that Anon154847 mentioned.