Mail Shield blocking SMTP

Avast Free Antivirus / Premium Security
1

I have had a recent update to Avast nagging for a reboot for a few days.

I rebooted the machine this morning. I went to send an email this evening and got an error that the connection was being lost before completion of the transaction.

I run my own mail server and checked the server logs - sure enough, see below. When I disabled Mail Shield for outbound email (still enabled for inbound), all works fine.

Outbound Mail Shield enabled:
Sat, 31 Aug 2019 23:41:06 → 10.x.x.x → Success: Action=[Accept Connection], Details=[Port 25]
Sat, 31 Aug 2019 23:41:06 → 10.x.x.x → Success: Action=[Received Hello], Details=[Host=[10.x.x.x]]
Sat, 31 Aug 2019 23:41:07 → 10.x.x.x → Success: Action=[Start TLS]
Sat, 31 Aug 2019 23:41:07 → 10.x.x.x → Success: Action=[Received Hello], Details=[Host=[10.x.x.x]]
Sat, 31 Aug 2019 23:41:07 → 10.x.x.x → Success: Action=[Starting Login], Details=[PLAIN authentication.]
Sat, 31 Aug 2019 23:41:07 → 10.x.x.x → Success: Action=[Login], Details=[xxxx@xxxx]
Sat, 31 Aug 2019 23:41:07 → 10.x.x.x → Success: Action=[SPAM White List Check], Details=[Sender is white listed.]
Sat, 31 Aug 2019 23:41:07 → 10.x.x.x → Success: Action=[Received Sender], Details=[xxxx@xxxx.com]
Sat, 31 Aug 2019 23:41:07 → 10.x.x.x → Success: Action=[Received Recipient], Details=[xxxx@xxxx.com]
Sat, 31 Aug 2019 23:41:07 → 10.x.x.x → Success: Action=[Start Mail Transaction]
Sat, 31 Aug 2019 23:41:07 → 10.x.x.x → Success: Action=[Close Connection]

Outbound Mail Shield disabled:
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[Accept Connection], Details=[Port 25]
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[Received Hello], Details=[Host=[10.x.x.x]]
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[Start TLS]
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[Received Hello], Details=[Host=[10.x.x.x]]
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[Starting Login], Details=[PLAIN authentication.]
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[Login], Details=[xxxx@xxxx]
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[SPAM White List Check], Details=[Sender is white listed.]
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[Received Sender], Details=[xxxx@xxxx.com]
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[Received Recipient], Details=[xxxx@xxxx.com]
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[Start Mail Transaction]
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[Complete Mail Transaction], Details=[From Host=[10.x.x.x], Size=1 KB, From=xxxx@xxxx.com, To=xxxx@xxx.com]
Sat, 31 Aug 2019 23:50:27 → 10.x.x.x → Success: Action=[Close Connection]

2

I have 3 accounts in my email client, two are hosted on my own private mail server, one is on a public server (AOL).

After posting this thread, I went back to the mail client and found that incoming email had also stopped working on the AOL account. The two accounts on my private server seemed OK (for now, at least). After disabling Mail Shield entirely (incoming and outgoing) the connection restored immediately.

I’ve also been having issues on an Android device in the past few days which has the Avast free mobile app installed - any coincidence likely, or is this unrelated?