There is no guarantee for this behavior, however. Email addresses can also react sensitively to case. If you send an email with the recipient's address spelt in the wrong case, it might return to you with a delivery failure. In that case, try to find how the recipient wrote their address and try a different spelling.
Of course, it is best not to let such frustrating situations develop. Unfortunately, email addresses are case sensitive in theory, and can — in rare occasions — also be in real internet life. Still, you can help minimize the problem, confusion and headaches for everybody.
Help Prevent Email Address Case Confusion
To minimize the risk of delivery failures due to case differences in your email address and to make the job easy for email system administrators:
- Use only lower case characters when you create a new email address.
If you create a new Gmail address, for example, make it something like "firstname.lastname@example.org" and not "J.Smithe@gmail.com".