How to avoid duplicates when donated using different email address or spelling mistake on names?
That is a difficult area. It touches on'the safest system is the one without users' :-) You can not avoid users making typos as far as I know, you will need to have a regular deduplication process in place. Here is the process we are discussing at one of my projects:


we want the data in the system asap, so we accept everything but all new contacts go in a separate group
we have a daily process for one of the employees, looking for dedupes on a daily basis (with a fairly strict rule first and a more fuzzy one second) and taking corrective action whenever required. If new contact is fine it is removed from the group.
I hope it helps :-)