So when I'm mentioned on a JIRA I'm not assigned I get a "X mentioned you" email.

When I'm mentioned on a JIRA I am assigned to I get a "X commented on" email and I have to parse the email and work out that I was mentioned. Importantly, this defeats my GMail filter and has on many occasions meant I've missed important mentions.

I think any mention should supersede a comment email as that is a more targeted operation and means simpler email filters.