Thanks even for that information. This is not an area I've ever dealt with before. (Was that English?).
I don't have access to active directory, but I can pass this part of it over to the people who look after it, and they may be able to create a lookup function.
What I meant by 'only addresses are in the form of' was that these strings occur in a database column labelled 'email address' and all other email related columns are blank/null.
I don't know who wrote the back-end for this package/database, but I would dearly like to meet them. To 'Remonstrate with them' in the perported words of St. Benedict.
Needless to say, there is no documentation.