I need to find a “simple” and “logical” way to find if mail being sent is going to someone inside my domain or external - other than by looking up on Domino Directory (user may be offline without full local directory).
In the first place, different top level Domains cannot be a common domain. Therefore, .org can’t be the same as .com (or its derivative .co). So john@ibm.org can’t be in the same domain as fred@ibm.com. I think I can get away with distinguishing between 4 TLDs (.co?, .net, .org, .gov).
Next, same organization in different countries could have .?? as two-digit country identifier. So for my purposes @ibm.com = @ibm.co.de = @ibm.com.au
Finally, some organizations put on a prefix before domain to indicate some structure. So for my purposes @work.ibm.com = @home.ibm.com.
And all combinations…
Am I making sense? Thank you very much for any guidance.