AVG VPN Greylisting on Mozilla Thunferbird

I am running the latest updated version of Windows 10 64bit and use Mozilla Thunderbird (also fully up-to-date) . Just recently, when trying to SEND emails I get a pop-up message saying I am greylisted for 900 seconds. This is only resolved by deactivating AVG VPN. Can you assist please.
Hello Geoff,

I understand the inconvenience.
Are you using the "Optimal Location" on Secure VPN or changed the location to different region.
Please provide the (screenshot) of popup that says about greylisted to assist further.
You can post the screenshot here in your topic. Click on 'Answer' & then click on the 'Image' [mountain symbol] & follow the instructions.

Hello Geoff,

I understand the inconvenience.
Are you using the "Optimal Location" on Secure VPN or changed the location to different region.
Please provide the (screenshot) of popup that says about greylisted to assist further.
You can post the screenshot here in your topic. Click on 'Answer' & then click on the 'Image' [mountain symbol] & follow the instructions.