Port 25 is blocked for SMPT email sending all (3) email accounts

I am using Outlook 2003.  I have three POP/SMTP accounts set up and all have been working fine until last week.  Now I can receive email from these accounts but I cannot send anything out from any of the three accounts.  I have confirmed that the SMTP settings are correct.  

Error message - Sending' reported error (0x800CCC0D) : 'Unable to find the e-mail server. Please verify the server information in your account properties.

My operating system is Windows XP Professional SP2 on this workstation.

When I test the telnet port I get the following message - Connecting To smpt.comcast.net...Could not open connection to the host, on port 25: Connect failed.  However, I am able to connect using port 587.  I attempted the same command using another XP SP2 in the same LAN and get the same results.

Also, I use MS Onecare and I believe that they did some upgrade last week.  That may be where the problem is but I can't find it.  

When I run the telnet command on the server I get the message - "Connecting to smpt.comcast.net...Could not open connection to the host, on port 25: Connect failed.  However using port 587 works.

Is there something in the Small Business Server software blocking port 25?
macoskiAsked:
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isaman07Commented:
Do you have Mcafee enterprise Installed? If yes make sure to remove the checkmark for the prevent mass mailing worms option in the access protection.
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macoskiAuthor Commented:
No I do not.
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TG TranIT guyCommented:
Have you checked with Comcast to see if they close up port 25?
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isaman07Commented:
Just curious, is your windows Xp firewall on? And what antivirus do you have installed?
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TG TranIT guyCommented:
Comcast automatically block port 25 if it detected 1000 msg with 24hr period - you need to wait 24 hrs for them to clear this block
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macoskiAuthor Commented:
I haven't but I have two different email accounts that also use port 25 and they don't work either.  So I've assumed that the problem is in my system or network.
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macoskiAuthor Commented:
I have waited 24 hours,
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macoskiAuthor Commented:
I've turned off the firewall and still get the same results.
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macoskiAuthor Commented:
The antivirus software I use is Microsoft's Onecare.
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TG TranIT guyCommented:
If you have tried telnet 25 on your server and still no joy, then check firewall or give Comcast a call
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wk_automatiseringCommented:
try mail.comcast.net

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DrDave242Commented:
Can you telnet to another (non-Comcast) mail server on port 25?  To find a good candidate, use nslookup.  Type the following commands in order at a command prompt:

nslookup
set q=mx
<well-known domain name, e. g., yahoo.com>

You should receive output similar to this:
Server: (Your DNS server)
Address: (Your DNS server's IP)
 
Non-authoritative answer:
yahoo.com       MX preference = 1, mail exchanger = d.mx.mail.yahoo.com
yahoo.com       MX preference = 1, mail exchanger = e.mx.mail.yahoo.com
yahoo.com       MX preference = 1, mail exchanger = f.mx.mail.yahoo.com
yahoo.com       MX preference = 1, mail exchanger = g.mx.mail.yahoo.com
yahoo.com       MX preference = 1, mail exchanger = a.mx.mail.yahoo.com
yahoo.com       MX preference = 1, mail exchanger = b.mx.mail.yahoo.com
yahoo.com       MX preference = 1, mail exchanger = c.mx.mail.yahoo.com

Open in new window

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DrDave242Commented:
You'll see some more info as well, but those servers listed are Yahoo's mail servers.  Now try to telnet to one of them on port 25.  If you are successful, outbound traffic on port 25 is not being blocked from your network.  If the connection fails, try another server or two.  If you can't connect to any of them, that port is definitely being blocked.  Do you have residential or business Internet service at that location?  It's quite common for ISPs to block port 25 for residential users.
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