I have this strange problem that has been plaguing me for almost a month. We have a small office (less than 20 users) that use Charter as an ISP - cable modem. We also have an external host, discountasp.net where we host our website and email. Once or twice a day we lose our ability to send email. We can receive email and browse the web but we cannot send mail. We get the following message:
Task 'email@example.com - Sending' reported error (0x800CCC0F) : 'The connection to the server was interrupted. If this problem continues, contact your server administrator or Internet service provider (ISP).'
(Usermail and ourcompany aren't the real names for privacy)
This problem will persist for about an hour and then it resolves itself and the sending problem goes away. Also, while the problem is occuring, I can connect to my Android phone hotspot and send and receive email just fine. In other words, when I use an ISP other than Charter, it works! Also, in a similar fashion, when at home on my ISP (not charter) email sending works fine. However if I connect to the VPN while the office is experiencing this sending problem, I also cannot send. Disconnect from the VPN (charter) and back to my home ISP (not charter) and sending works again.
You might say, viola, it's the ISP Charter. However, when I contact Charter they state there is nothing wrong on their side. When I contact Discountasp.net they have me perform a tracert to the smtp server which works fine, no drops. And they have me telnet to the smtp server which also works fine. So they then state there's nothing wrong on their side.
Anyway, I'm at a loss. I'm at the point of switching ISP's from Charter to anyone else in order to solve this problem.
Just thought I'd put this problem out there to see if anyone has actually fixed the issue and can save me the headache of switching ISP's.
BTW - it has nothing to do with the outgoing port being 25 or 587, either setting produces the same error.
Also, during the problem i've tried restarting our one domain controller, our modem and our WIFI router thinking it could be an internal issue - didn't help.
SOME MORE INFO--- Having the problem occur again today I decided to try sending from a different account and it worked. So the problem is narrowing down. The problem occurs when trying to send email using discountasp.net's smtp server. If I switch accounts, using different SMTP server, then I can send. So the problem only occurs when using discountasp.net's smtp server. Howerver, if I switch ISP from Charter to my phone hot spot then I can send just fine using discountasp.net's SMTP server. A real mind boggle.