You can do a DuckDuckGo Search (or snooptastic Google, if you prefer) on “e-mail address validation regex” (try removing the word regex or replacing with the full word, or the word “pattern” or “parsing”) and you should get a lot of hits. The most comprehensive validator that I’ve found was written in C# for CLR / dotNet: it could handle ALL valid internet e-mail addresses, including those with complex domain names.
That particular regex had several drawbacks:
- excessively long regex (in the neighborhood of 200-300 characters!)
- thus incredibly complex and difficult to proofread or to troubleshoot.
Personally, I’d prefer having to copy a hundred lines of parsing code (if relatively straightforward and clear) than to try to get such a fierce regex working. It can, however, be done!