I updated to version 7.0 (39134) and the mail shield once again prevents IMAP email from coming through. I was working fine up to this version. The only way to get the mail shield to work is turn it off then turn it back on. It seems to work for a while but then the Mac goes to sleep and the Mail shield mail functions. I then updated today to 7.0 (39141) and still have the same problem. It looks like a return to the problems we had months back. I think it has something to do with the way Avast is now using IPV-6. It always worked prior to these updates but now if I disable IPV-6 Avast will allow mail to pass through Thunderbird and Mail, if I in able IPV-6 after a short while it will stop allowing mail to be delivered.
joelw135…this does seem to be more common than I first thought…I spoke to Apple and my ISP about this issue but have concluded that it is an Avast issue. See my post here. I have found that switching off both the IPv6 and the other option in the Mail Sheild advanced tab is the only way I can get it to allow the delivery of emails. Very frustrating and if it starts to cause the same issue again in the future, Avast will be removed off my Macs.