Has newsleecher previously worked with avast ?
I don't know if this might be related to issues with newsleecher and avast from before - The supersearch uses a protocol other than NNTP on port 119 and that is a problem for the mail scanner. The workaround is the option "Use alt. supersearch port" in NewsLeecher options or to put the address 70.86.176.98 to the AvastUI, Settings, Troubleshooting, Redirect Settings, Mail, ignored addresses. Note: there may have been a change to the IP address, if that one doesn't work, try this one, 174.37.197.132 (or you will have to identify what it is using currently).