Their sheet[1] of affected clients shows Thunderbird as WONTFIX, but that label is on only one of five bugs in bugzilla relating to mailsploit[2], specifically 1423440[3] for which I think the WONTFIX rationale is correct:
> There is nothing wrong with having: "Men @ Work" <menatwork@example.com>
> People use this and complain if it doesn't work, see bug 1359774.
1. https://docs.google.com/spreadsheets/d/1jkb_ZybbAoUA43K902lL...
2. https://bugzilla.mozilla.org/show_bug.cgi?id=1423430
3. https://bugzilla.mozilla.org/show_bug.cgi?id=1423440
