ISP may be blocking port 25--I'm not sure

[MichaelD]

This problem started two days ago. I'm running Outlook 2003 SP3 and have been for two years now. I've had no problems until now. Nothing in my PC or network has changed; no new hardware or software/patches.

I have hosting (IXWEBHOSTING.COM) that my domain resides with and that processes my email. I'm just a single user...I'm not running a huge mailorder business or anything like that. I put in a ticket with them and they say everything is fine on their end, that it's either me or my ISP. My account with them is fine, server is not full, nothing blocked, etc. I store no mail on my hosting's servers; I DL everything in real time with Outlook.

I can receive all email just fine but I cannot send; I get the standard "Outlook cannot connect to your outgoing SMTP server" popup. If I login through webmail (www.mail2web.com) I can send thru them, so my SMTP relay thru my hosting seems fine.

I have tried to telnet to my mailserver/25 and cannot. I have logged into my Gateway/router at home and everything is as it has been; nothing is blocked. Even rebooted the router twice just to be sure. I have disabled Symantec Endpoint Protection (and checked it's logs), I've run an Office Repair just in case...nothing. I can receive but not send.

It looks like my ISP is at fault here...or are they? Would you please help me with some additional troubleshooting? I've tried everything I know.

Thank you!

 

[skyking]

It sounds quite plausible from what you've done so far, have you contacted them yet? I typically use the ISP's mailservers for outgoing mail anyway.

 

[Modelworks]

email isp. If they are blocking the port contact your webhost and ask if their is an alternate port you can use.

Many webhost do not allow you to send mail . That is why I went with steadfast.net. They allow me to send mail through their servers as part of the package.

 

[MichaelD]

Thanks very much, guys. It makes me feel better that I haven't missed something obvious. I will work on contacting the ISP.

 

[JackMDS]

As an interim solution check again with your Host service.

My Host email has a Dual POP3 & Webmail capacity. I.e. if I am in a situation that I can not use Outlook I can log to my WebMail the way one log to GMail etc. and use it.

 

[spidey07]

Do this. Telnet to port 25 on your SMTP mail server. If it answers or you don't get an immediate disconnection then the port is not blocked.

telnet mymailserver.domain.com 25
HELO

-edit-
see you've already done this. You could also use wireshark to get a packet capture to see exactly what is going on.

 

[MichaelD]

Thank you, JackMDS and spidey07. I'm really happy that you guys read and replied. This is an interesting situation. The more I dig, the more I see it's my ISP.

I've emailed my ISP and am waiting for them to reply.

 

[DrGreen2007]

Have you tries setting your Outlook to send on the other SMTP port, think its 587?
I had to do that with 1and1.com (my webhost) because AT+T (isp) was blocking 25

 

[MichaelD]

Originally posted by: DrGreen2007
Have you tries setting your Outlook to send on the other SMTP port, think its 587?
I had to do that with 1and1.com (my webhost) because AT+T (isp) was blocking 25

Thanks very much. My hosting suggested that I try enabling SMTP Authentication in Outlook but they DIDN'T specify port 587. Ironically, I just discovered that SMTP Authentication uses port 587 and not 25; I'm doing a bit of research on this issue from work.

There is a possibility that my IP range is on a blacklist somewhere; I've encountered this problem before, but at work. I'm not in the states, so solving these problems is a lot more difficult, unfortunately. There is only one ISP here so there's no other options as far as "just getting a new ISP" goes.

I wish I was home so I could check what my modem's IP is and check it against known blacklists at spamhaus.org, for example.

I will try SMTP Authentication/587 when I get home.

Thanks again.

 

[RebateMonger]

In the U.S., it's VERY common to have ISPs block outgoing communications to SMTP servers on their TCP Port 25. It's gotten to the point where it's considered "bad Internet manners" to allow non-businessl clients to send directly to SMTP servers other than the ones controlled by the ISP. Supposedly 90+% of all SPAM comes from home PCs that have been infected with malware, so restricting their outgoing mail to the ISP's mailservers makes sense, although it's a PITA for the rest of us.

 

[TheKub]

Originally posted by: RebateMonger
In the U.S., it's VERY common to have ISPs block outgoing communications to SMTP servers on their TCP Port 25. It's gotten to the point where it's considered "bad Internet manners" to allow non-businessl clients to send directly to SMTP servers other than the ones controlled by the ISP. Supposedly 90+% of all SPAM comes from home PCs that have been infected with malware, so restricting their outgoing mail to the ISP's mailservers makes sense, although it's a PITA for the rest of us.

I had a similar issue with sending email via my webhost when I had AT&T DSL after searching around for several hours I found out that they just had a form\waver\opt out or something you had to fill out online and they unblocked you. Was a couple of years ago so the details are a bit fuzzy.

 

[MichaelD]

I have wireshark but I'm not sure how to use it. Would someone please tell me what to do so I can definitively identify that port 25 is blocked?

Thanks.

*edit*
DAMMIT! Windows7 is not supported by WinPcap. :| I tried both the 32 and 64 bit versions of wireshark. Any other ideas?

 

[TheKub]

Who is your ISP?