I am trying to send an email. Every time I try to put a contact in the ‘to’ box it says unexpected error after one letter being inputted. The ‘to’ box goes light grey
This would appear to be a new fault with the BTMail. Accounts that were previously working correctly when composing an email are now doing as stated by the OP. It does not appear to affecting every BTMail account.
If it does not "fix" it self by tomorrow and assuming the moderators do not comment on this thread I will inform them about the problem.