OWA has a known issue with Firefox on Linux where it incorrectly believes that Ctrl is pressed while typing an email. This results in frequent missed characters and spurious actions, including moving focus to the search bar, archiving messages, saving the current message as a draft and closing it, etc. This makes OWA extremely frustrating to use. Another issue with OWA is the unhelpful completions (which I've noted before on HN), which in my experience seem to be related to the spurious actions (more suggested completions = more spurious actions)