I will pay attention to if this resurface. I am using the latest version/build already as in my signature.
I am an ADSL line. Perhaps because the line was disconnected somehow...I will monitor if this happens again as I said.
EDIT:Q: How do you connect the Internet?
A: ADSL
Q: Is there any file attached to that mail?
A: No.
Q: Which is the email account timeout (Advanced tab of the email account properties) ?
A: 300 seconds