To sort mails by name or date the options button has to be clicked first. In the use tests this led to irritations.

Proposal:
The sorting function could be arranged in an own bar above the mail list. This would create a higher spacial proximity between the instrument (sorting function) and its location of impact (mail list) and therefore the mental connection would be more obvious. Furthermore the mails could be sorted e.g. by name just with one click on the name button (see screenshot). For more options (e.g. change from alphabetically increasing to decreasing) a click on the triangle button besides could open a corresponding drop down menu.