re :On my MAC, whenever I go to any new webpage

That sounds like you are using a browser of some unknown type eg: Chrome, Firefox, etc. You perform a search and select to see a webpage. So, is this pop-up occuring in the browser? Please post image if it helps explain what you are doing and shows the pop-up in question.

what do you mean by 'whenever I go' ? What action are you performing in Thunderbird? In Thunderbird, are you clicking on a link in an email which opens a webpage in a browser ?

Hello Toad-Hall. I use Safari on my Mac Mini. It seems to only happen while using Safari.

Mostly I get it on my home page of CNN.

But it also happens when I go to type in a different website – the background of the page goes dark – and that pop-up comes on. (See attached pic.) It does not allow me to go any further until I answer/click on a response. I have to click on “cancel" to get rid of it - and move on, and if I click on “allow”, it will open and bring me to my email page in Thunderbird. I did not get it when I used Chrome - I use Thunderbird for my business email only. I use gmail for most of my personal email. But I use Safari as my prime web browser. Thank you. Bruce

This is not a Thunderbird problem. It is Safari. Apparently a new security policy of Safari (in 10.12.2+) and as yet I'm not so sure there is any workaround.

I found similar cases:

• https://kb.pulsesecure.net/articles/Pulse_Secure_Article/KB40736
• https://stackoverflow.com/questions/41620802/how-to-mitigate-safari-warning-do-you-want-to-allow-this-page-to-open-xyz/42207719
• https://apple.stackexchange.com/questions/265267/how-to-skip-safaris-do-you-want-to-allow-this-page-to-open-x-dialog

https://support.clio.com/hc/en-us/articles/360008824914-Safari-Google-Chrome-Keeps-Asking-Do-you-want-to-allow-this-page-to-open-Clio-Launcher-

I could produce loads more examples, but the only way to get around this is to set another browser as default.

Well it’s good to know that I’m not the only one! But this is definitely a problem. I’m going to start talking-to Apple about it... If by chance I should get anywhere, I’ll post you and this forum. Thanks for your help with this. I wish you good health! Stay safe. Regards, Bruce

SOLVED – I went to the APPLE Safari trouble shooting site and this issue is all over the place. While no one can actually tell us why this is happening, it seems they have found a solution: CLEAR YOUR BROWSING HISTORY. That’s it. Something in there is causing it. So far I am no longer getting the pop-up. We will see if this is a permanent fix – or if the problem returns. Thanks again. Stay Safe. Bruce