Office 365 ATP activating unsubscribe links


We use Mailchimp to send email alerts to journalists. 

Recipients from 3 specific news organisations are being automatically unsubscribed. We have confirmed that they are not clicking unsubscribe, nor have they forwarded an email to someone who might have clicked. It is not affecting subscribers in other news organisations.

Nothing is happening at our end except having Mailchimp respond to unsubscribe requests, which we are legally obliged to do.

investigations seem to have narrowed down the issue to Office 365 advanced security features.

According to, O365 Advanced Threat Protection "now goes further and analyses the web address for any signs of malicious content".

It seems that ATP is following the unsubscribe link to check the site, thereby activating the link.

Is there a solution I can pass on to the sysadmins of the affected organisations?


Hi John,

To clarify, for example, if the Mailchimp sender is "", you can contact the affected organization's admin to add the to be their safe sender. And you can deliver the information to them.




* Beware of scammers posting fake support numbers here.

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Question Info

Last updated April 21, 2021 Views 1,576 Applies to: