Outgoing SMTP (port 25) blocked ?
 

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.

Re: Outgoing SMTP (port 25) blocked ?
 

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

Re: Outgoing SMTP (port 25) blocked ?
 

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.

Re: Outgoing SMTP (port 25) blocked ?
 

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.

Re: Outgoing SMTP (port 25) blocked ?
 

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.

Re: Outgoing SMTP (port 25) blocked ?
 

<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)

Re: Outgoing SMTP (port 25) blocked ?
 

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 ?

Re: Outgoing SMTP (port 25) blocked ?
 

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 )

Re: Outgoing SMTP (port 25) blocked ?
 

How about giving us the error your receiving

Re: Outgoing SMTP (port 25) blocked ?
 

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

Re: Outgoing SMTP (port 25) blocked ?
 

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 !

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. :)

Re: Outgoing SMTP (port 25) blocked ?
 

Welcome to nthellworld.co.uk :welcome:

Re: Outgoing SMTP (port 25) blocked ?
 

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

Re: Outgoing SMTP (port 25) blocked ?
 

Thank you very much...glad to be here :)

Re: Outgoing SMTP (port 25) blocked ?
 

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

Re: Outgoing SMTP (port 25) blocked ?
 

Both NTL dns servers are [currently at least] returning the correct mx records for hotmail.com

Re: Outgoing SMTP (port 25) blocked ?
 

NTL could block incoming port 25 to customers and no one, apart from people like myself running their own mail server, would know or care.

Also blocking outgoing port 25 is feasible providing that they undertook some form of packet filtering to allow port 25 traffic to their own mail servers but no where else.

I don't think the NTL network is so advanced as to allow this sort of filtering but if it is then theoretically they could do it without affecting 99% of their customers.

Re: Outgoing SMTP (port 25) blocked ?
 

Any router could potentially block as you suggest, and I'm sure that ntl could do it if they wanted, but they are not. As has been suggested elsewhere, how about a verbatim copy of the error message so we can find out where the problem actually lies?

Re: Outgoing SMTP (port 25) blocked ?
 

Sorry Jimbo I wasn't insinuating that NTL was blocking port 25 I was simply trying to correct Dooby's assumption that you couldn't block port 25 and still allow email to flow.

Re: Outgoing SMTP (port 25) blocked ?
 

DVS

There are some people that do run there own mail servers. The problem is caused by newbees that set up nice open relays. I agree they need to be stopped !!! but not at the expense of users that are responible and use there mail servers correctly. Most people only run mail servers of there own cos there sick of NTL'S crappy mail servers.

Re: Outgoing SMTP (port 25) blocked ?
 

Might be worth checking your firewall to see if your e-mail is being blocked.

If you have something like SpamPal or Mailwasher it's possible that your firewall is mistakenly blocking that, hence no e-mail.