[iamstac3y]

Noticed on different occasions that after moving to trash and then also deleting from trash it seems to somehow a while later just reappear again.... I've got my icloud and Gmail it happens with both accounts

[Ledsteplin]

That's a common issue. You can go to your email accounts online in Safari and delete those emails there. They should then stay deleted.
I don't know what the fix is. I've had this happen before, but don't know what fixed it.
Try going to Settings >Mail, Contacts and Calendar > your email account > Toggle OFF Mail> then toggle it back on.
If that doesn't work, try deleting the email accounts, then add them back in.
You could also try Reset All Settings.
Reset All Settings
Go to Settings >General >Reset >Reset All Settings. This resets to default everything in Settings, including notifications, alerts, brightness, and clock settings like wake up alarms.
Other than that, a restore of your phone as new might be needed.