We had a new tester start today so I set up his machine and he started working through one of our admin databases - the access requests. Unfortunately I forgot to switch the mail location in Lotus Notes so as the tester was merrily rejecting and approving test access requests, e-mails were being sent out to end users informing them that their request was unsuccessful.

Most embarrassing. Luckily the support team saw the funny side of it and know how to deal with mystified users asking why they have been rejected for something they didn't even request in the first place.