I just checked out the pEp android app (installed over F-Droid) and imported my accounts from my K-9 Mail app.
Right now the way to switch between accounts is by open the drawer and click on the account icon in the top or first click on the down arrow next to the current selected account to then get a list of all the other accounts.
Since I use the same name for all the accounts and it starts with 'T' all the account avatars look the same:
It would be nice to (automatically or give an option to) assign each account a unique color in order to improve multi account usage!
Even I if a do the extra tap on the arrow pointing upwards and get the list of my other accounts I it would be much easier to distinguish the accounts if they had a unique color each.
Evermore I would suggest to change the appbar's or/and the drawer header's background color to generally indicate which account is active.
