topic block yahoo mail in Next-Generation Firewall Discussions

block yahoo mail

Andrew-Hiser — Wed, 04 Oct 2023 17:02:50 GMT

Hello Everyone,

Does anyone have a way to block Yahoo web-based email without enabling decryption?

1. I have read through the forums, and tried blocking with a URL Profile with the following url configs.

*.mail.yahoo.com

*.mail.yahoo.com/

mail.yahoo.com

mail.yahoo.com/

*.mail.yahoo.com/*

mail.yahoo.com/*

2. I have also tried just blocking standard webbased email in the default URL category. I also tried denying yahoo mail base via a securtiy policy.

None of the above works unless Decryption is enabled on the Palo. Basically they can go to Yahoo.com and click on the mail icon and get there. Unfortunately I can't block the login screen becuase they need for other parts of Yahoo (ie Yahoo finance). Any recommendations would be appreciated. Unfortunately the customer doesn't want to enable Decryption.

Thanks in advance for all of you advice.

Re: block yahoo mail

BPry — Wed, 04 Oct 2023 17:15:09 GMT

@Andrew-Hiser,

If you can grab a test client and associated a url-filtering profile that has everything set to alert, you should be able to see exactly what the firewall is seeing as far as what URL clients are visiting. You should be able to use those logs to build out a block at that point, or confirm that you won't be able to block it without affecting access to the other Yahoo services that they need.

Taking a brief glance at unencrypted traffic matching mail.yahoo.com, looks like you should be able to block this with what you have. Ensure that your deny rule also accounts for the traffic being identified as yahoo-mail and not just ssl/web-browsing.

Re: block yahoo mail

Andrew-Hiser — Wed, 04 Oct 2023 18:26:40 GMT

I did find all of the websites it was reaching out to (screen shot is below). I did put all of those websites in the URL filtering profile as a block (added them with wildcards and Carets as well). When I log in to Yahoo, I can still get to the Mailbox (screen shot of that below as well). The only way I that is blocked is if I enable Decryption on the firewall. I have denied traffic to all yahoo mail bases on any service through a policy and the mail link in the screen shot below still goes to my mailbox.

Re: block yahoo mail

OtakarKlier — Thu, 05 Oct 2023 21:55:13 GMT

Hello,

On your URL filter, you can just block web-based-email category. If you need to allow any, just put the allowed websites above that policy.

Regards,

Re: block yahoo mail

MSmith13 — Tue, 10 Feb 2026 10:31:46 GMT

I have been trying to block this for about two years now. I think it's because of the bouncing around that Yahoo does to CDN's. The app-ID doesn't work, the web-based-email category doesn't work (for yahoo mail), and blocking the domains in URL filtering does not work. I added login.yahoo.com to the blocklist and under certain circumstances it helps, but ultimately this is something Palo Alto needs to address.

Re: block yahoo mail

MSmith13 — Tue, 10 Feb 2026 13:38:33 GMT

Update - I added s.yimg.com/ and the TLD of yahoo.com to the decryption policy, and I think that is effective enough to prevent access to Yahoo mail (on top of all the other block settings).