Outgoing SMTP (port 25) blocked ?

ColmanC · 12-12-2003, 15:46

I'm running my own smtp server behind an NTL 600K service (long story...and largely irrelevant to this issue). A ouple of weeks ago I started having problems sending emails...they would all bounce back saying that the destination server could not be found. We're not talking about obscure addresses here either...the likes of hotmail.com and yahoo.com aren't working.

Additionally, when I try to telnet to hotmail.com port 25 then nothing, although hotmail.com port 80 works.

My assumption is that NTL have starrted blocking outgoing port 25 traffic. Anyone know if this is true...and why ? It's not a show-stopper of a problem, I can simply re-configure my mail client to send via NTL's smtp server, but I like having the freedom to choose.

Many thanks in anticipation.

tkiely · 12-12-2003, 16:14

sounds like a dns issue to me? can you send from outlook express to the ntl mail servers? if you can then they havn't blocked anything.

T

Enterian · 12-12-2003, 16:18

Sounds like a port block to me a DNS issue will affect ALL traffic regardless of port. Probably a heavy handed attempt to stop NTL users running open mail relays.

ColmanC · 12-12-2003, 16:18

I can ping, for instance, hotmail.com and the address is resolved into 64.4.52.7, and all web browsing is fine. It's just outgoing mail from my smtp server that's a problem. And like I said I can send from my mail client to ntl's smtp server no problem.

ColmanC · 12-12-2003, 16:21

Quote:

Originally Posted by Enterian

Sounds like a port block to me a DNS issue will affect ALL traffic regardless of port. Probably a heavy handed attempt to stop NTL users running open mail relays.

My fear precisely. Oh well, work have installed a BT Openworld line for me so I can work from home so I might just get rid of my cable service altogether. The freedom to run my own servers was attractive, but less so now.

Thanks to all for your responses.

**Paul** · 12-12-2003, 16:40

<sigh> how many more of these threads before it sinks in. NTL are only blocking the ports they have listed and only incoming.

Port 25 is working fine to every network I can think of in the last 10 mins.

(and that includes hotmail whose mailservers are at mx1.hotmail.com, mx2.hotmail.com, mx3.hotmail.com & mx4.hotmail.com)

ColmanC · 12-12-2003, 16:49

Quote:

Originally Posted by pem

<sigh> how many more of these threads before it sinks in. NTL are only blocking the ports they have listed and only incoming.

Port 25 is working fine to every network I can think of in the last 10 mins.

(and that includes hotmail whose mailservers are at mx1.hotmail.com, mx2.hotmail.com, mx3.hotmail.com & mx4.hotmail.com)

Sorry if I've gone back over old ground, I've just joined and a search on port 25 issues did not reveal anything.

Nonetheless, whilst revealing that there is no blocking of port 25 outgoing, you haven't suggested what the actual problem might be. Any suggestions ?

Dooby · 12-12-2003, 16:52

even a standard mail program sends email by connecting out on the SMTP port, blocking port 25 would result in noone being able to send email (unless they used a webmail client or something )

Mr.Moony · 12-12-2003, 17:36

How about giving us the error your receiving

threadbare · 12-12-2003, 18:26

why does everyone with a problem automatically assume it is a bloked port? as if ntl are going to block port 25!!!

**Paul** · 12-12-2003, 19:41

Quote:

Originally Posted by ColmanC

Sorry if I've gone back over old ground, I've just joined and a search on port 25 issues did not reveal anything.

Not really old ground - it's just that everyone who cannot connect to something these days seems to jump straight in and accuse NTL of blocking ports !

Quote:

Nonetheless, whilst revealing that there is no blocking of port 25 outgoing, you haven't suggested what the actual problem might be. Any suggestions ?

That's because you haven't given enough information so anything I suggested would be pure speculation - so instead I suggest you post some actual examples of the error messages and any associated error codes they may have, then people will have something to work with and hopefully shed light on your problem.

**Mick** · 12-12-2003, 19:44

Quote:

Originally Posted by ColmanC

I've just joined.

Welcome to nthellworld.co.uk

Stuartbe · 17-12-2003, 08:58

Have you tried to telnet to a mail server using the IP instead of the domain name ?

ColmanC · 17-12-2003, 20:36

Quote:

Originally Posted by Dr. Plummer

Welcome to nthellworld.co.uk

Thank you very much...glad to be here

ColmanC · 17-12-2003, 20:39

Quote:

Originally Posted by stuartbe

Have you tried to telnet to a mail server using the IP instead of the domain name ?

Just did and it worked fine. Then again telnetting to mx1.hotmail.com on port 25 works too. I guess there is a DNS issues where the ...@hotmail.com address isn't resolving to the actual SMTP servers (MX records ?), but not being too hot on DNS I get lost just about there

Looking more and more like an internal issue, although I am using the standard NTL DNS servers (194.168.4.100 & 194.168.8.100)

Colman