Mail Shield Disrupts Gmail Accounts In Outlook 2019, Works Fine For Others

I’ve seen a lot of threads related to the Avast Mail Shield causing issues with various email clients, but I wasn’t able to find a solution that solves the problem completely. If I missed it, I apologize.

In addition, my issue seems to be a bit different since it is not specifically email client related as much as it is email server related.

I am using Outlook 2019. I have email addresses with 3 different email providers: Gmail, StarNova (eznet.net) and outlook.com. A few months ago I started having sync problems with my 2 Gmail accounts, but not with the others. I would receive sync errors (synchronizing with subscribed folders was unsuccessful), there would be long delays in receiving gmails (like hours long delays), outgoing mail would get stuck in my Outbox, etc. Creating new Gmail accounts was hit or miss with varying errors showing up each time. The most typical error was related to the type of IMAP encryption method that I was using even though all server settings were correct. Not once did I have a problem with the eznet.net or outlook.com email addresses, even when starting from scratch and creating a new Outlook profile. It was consistently only the creation of the Gmail accounts that presented the errors until eventually, with nothing being changed, the accounts would suddenly be successfully created. However, once the accounts were created, the sync errors and delays would start up.

Disabling the Avast Mail Shield resolves all the issues. Enabling it again brings all the problems back immediately. That part is reliably consistent.

Does anyone know of a reason why the Avast Mail Shield causes these issues and only with Gmail? Is there any other troubleshooting steps I can take other than simply enabling/disabling the Mail Shield? All that does is prove that the issue is related to the Mail Shield/Gmail but does nothing that leads to a solution.

Thanks for any advice that you can offer.