FYI - From https://en.wikipedia.org/wiki/Email_address Although the standard requires the local-part to be case-sensitive,[1] it also urges that receiving hosts deliver messages in a case-independent manner,[2] e.g., that the mail system in the domain example.com treat John.Smith as equivalent to john.smith; some mail systems even treat them as equivalent to johnsmith. [3] Reference [3] is to google saying that periods/dots in the local part are irrelevant. The wikipedia page cites RFC 5322. This page https://stackoverflow.com/questions/9807909/are-email-addresses-case-sensiti... says: So yes, the part before the "@" could be case-sensitive, since it is entirely under the control of the host system. In practice though, no widely used mail systems distinguish different addresses based on case. and cites RFC 1035 for the part to the right of the @ being case-insensitive. I sympathize with Peter getting gmail not for him, but that likely has nothing to do with capitalization and periods. People are just sloppy and forgetful. And in Karen's case, it should be the case that karenlewellen@gmail.com and karen.lewellen@gmail.com are equivalent and interchangeable (except possibly when signing in to gmail I suppose). So there may be something else unexpected that she's experiencing. Hope that helps! John