I received 2 emails titled "[JapanDict - Japanese Forum] V1zi3r accepted Your answer" at 12:22 PM and 8:26 PM EST on 5/27/18 despite having my notification preferences set entirely to popups.
Thanks for reporting this. I'm investigating it and it looks like it's an issue with the Q&A plugin. I'll try to find a fix as soon as possible.
I think I've solved the issue. Apparently it's not possible to avoid receiving an email when the question has been marked as 'valid', so I've completely removed email notifications for this feature. You will still receive a popup notification though.
Please let me know if you keep receiving emails.