Cookie functionality is a setting that allows (in this case) comcast.net to store bits of information on your browser. These can be deleted later if desired. To allow cookies on your browser, enter about:config in your address bar. Search: network.cookie.enableForCurrentSessionOnly (if you want to enable it only for that session (you won't be checking your mail more than this once))

network.cookie.alwaysAcceptSessionCookies (if you are planning on checking your mail on a browser often)

Double click the result that comes up to change the value from false to true.

Comment back if these directions don't make sense, or if you would like a screenshot.

Have a great day!!

Jon

Also, in case you didn't see it while posting your question, we have this help article: Websites say cookies are blocked - Unblock them.

Please note that some privacy oriented add-ons may override Firefox's standard cookie settings. In case one of your extensions is involved, could you test the problem sites in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset).

Any difference?

But I should add that Microsoft Office Outlook (if that's the Outlook you're using) connects directly to your email provider and doesn't use Firefox, so while it is worth fixing the issue in Firefox so you can use webmail normally, that might not help with Outlook.