This laptop runs FreeBSD 12.0 current. The version of the installed Firefox is 59, which is pretty new isn’t it? Well, that’s not new or good enough to browse email. What happened is that, the Outlook web based email would just automatically switch to class Outlook web access. This problem is not unique to Outlook email, even some work related websites refuse to load correctly on Firefox running FreeBSD.

A very easy work around is to set the User-agent of the Firefox on FreeBSD to the one running on Linux. In the past, I used some Firefox plugin to change the User-agent. Today, I just found out that I don’t even need the plugin.

According to this guide, to change the Firefox User-agent do the following step:

  • Run Firefox, and open a new tab
  • Add a new string by right clicking on somewhere in the tab and select New -> String
  • For String: general.useragent.override
  • For Value: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:53.0) Gecko/20100101 Firefox/59.0

After the changes made, Firefox does display the Outlook 365 email correctly.

Ref: how to change freebsd firefox user agent to linux firefox