When submitting the mail limit with enter instead of the button "Save limit" the bandwith got saved instead of the mail limit.

- Mac OSX
- Chrome 66

Steps to reproduce
- Login as admin
- Edit a user (CMD_SHOW_USER?user=<username>)
- Put cursor in field before " / Day" in row "Sent Emails"
- Change the value
- Press enter

Actual result:
Temporary bandwidth increase has been set

Expected result:
E-mail limit should be set