Connectivity
Connectivity and managing Your Comcast Business network
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Doc
New Member

Port 25 blocked outbound?

I'm trying to get my mail server working with my new comcast service, and it appears that port 25 outbound is being blocked?

 

I can sniff the packet leaving a remote destination on the Internet, arrive at my system, the response going back out, and then the response never arriving at the remote destination.

 

This is a huge show stopper for me. How can I get this turned on?

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6 REPLIES 6
Trusted Forum Contributor

Re: Port 25 blocked outbound?

here is a list of blocked ports on the Comcast network:

 

http://businesshelp.comcast.com/help-and-support/internet/ports-blocked-by-business-class-internet/

 

At the bottom, you'll see that occassionally, port 25 will be blocked due to spam. It appears you can call 1-877-807-6580 if you are running a mail server, and i would imagine COmcast would remove the block.

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Trusted Forum Contributor

Re: Port 25 blocked outbound?

Hello Doc and welcome,

 

Yes, Industry (including Comcast) now blocks port 25 due to a recent major hacking incident. As a result your email outgoing server can be re-programmed to either port 587 or 465.

 

Hope this heps you out.

 

 

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palmeris
New Member

Re: Port 25 blocked outbound?

So we have been using port 25 for outbound traffic on our HP CM2320nf Multi function printer for several years and today it seems that all traffic has been blocked?

 

We can not use any port that requires authentification of username and password as the HP laser printer does not give you any option for that, when i put in port 587 the devices says it passes the smtp gateway test but as soon as you try to send anything it fails to connect, presumably because the HP cant provide the authitification credentials.

 

Short of buying a new MFP device what can be done, is there other open ports, other solutions? We use this device daily in our business and any help is appreciated

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Trusted Forum Contributor

Re: Port 25 blocked outbound?

have you tried calling the number I mentioned in my post earlier in this thread? According to that Comcast page that lists all the blocked outgoing ports, you can call that number and request the block be removed.

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palmeris
New Member

Re: Port 25 blocked outbound?

THANK YOU - for that, i just got off the phone - they reprovisoned the modem and we are back up.

 

thanks for providing the number and beating me over the head with it - LOL

 

 

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Trusted Forum Contributor

Re: Port 25 blocked outbound?

lol no problem.

keep in mind, port 25 is permanently blocked using IPv6; this is due to technical problems on Comcasts end. I doubt your printer is using v6, but just in case, that phone # wont help there.
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