Neither of these situations should happen as long as the antivirus has new definitions. Many antivirus products don't have email scanning functionality anymore because it is caught by the realtime engine. When that email comes in a process writes the email attachment to disk using standard Windows APIs and it will get caught then. Not to mention most people use webmail nowadays which further removes the point of email client antivirus plugins.

In my opinion the risk is not worth worrying about.

I had a similar problem with Avast Internet Security after an update in November. No POP3 email received and Outlook 2007 was giving an error message about a program conflict. Turning off scanning did not resolve this permanently. You could get emails for one download and the next time the machine restarted email was blocked again

I found Avast had changed DNS from normal UDP requests to an HTTPS client accessing their own DNS servers. When I disabled this feature (somewhere in the settings) email came back to life and has remained so. Some hours wasted finding this.

[edited for typos and incident date added]

Edited by jtevans (Mon 23-Dec-13 13:15:33)