I have Firefox 35.0.1 and OS X Yosemite 10.10.1

On Firefox, I cannot browse to webmail.oxfam.ca.  I can do so on Safari on the same computer but on Firefox, the wheel just spins, Connecting... and eventually it times out and I get a blank page with an error message.

I've looked for solutions on line having to do with supported browsers, changing History and Security settings, and I can't find the solution. Cookies and cache have been cleared.

I can get to OWA on my other Mac on Firefox.  It's running Mavericks instead of Yosemite and the add-ons/plug-ins are a bit different from between the 2 Firefoxes but don't know which ones - if any - to change.

Any suggestions?

Hi HewsieQ37,

According to your description, I understand that you cannot use Firefox 35.0.1 logon OWA on Mac, however another Mac with same version works fine.
If I misunderstand your concern, please do not hesitate to let me know.

Firefox is supported for Outlook Web App when it runs on Exchange 2013, for your reference:
https://support.office.microsoft.com/en-us/article/Outlook-Web-App-%E6%94%AF%E6%8C%81%E7%9A%84%E6%B5%8F%E8%A7%88%E5%99%A8-7bb72d5f-0b1d-47f6-bd6f-2623ab3aeed8?CorrelationId=9751a8d8-22ab-4e56-bf9a-422559b1419c&ui=zh-CN&rs=zh-CN&ad=CN

Besides, since other Mac with same browser works well, it indicate that the issue may be related to client.
During my research, I suspect the problem may be caused by Mavericks.
Please try to update to latest version, meanwhile you can contact Mac support team so that you can get more professional suggestions.

Best Regards,
Allen Wang