Email, Messaging, & Video Calls Email 301 301 people found this article helpful Are Email Addresses Case Sensitive? Generally you can use just lower-case letters by Heinz Tschabitscher Writer A former freelance contributor who has reviewed hundreds of email programs and services since 1997. our editorial process Heinz Tschabitscher Updated on November 09, 2019 reviewed by Jerrick Leger Lifewire Tech Review Board Member Jerrick Leger is a CompTIA-certified IT Specialist with more than 10 years' experience in technical support and IT fields. He is also owns an IT firm in Texas serving small businesses. our review board Article reviewed on Mar 04, 2020 Jerrick Leger Email Yahoo! Mail Gmail Tweet Share Email Every email address has two parts separated by the @ sign: the username and the email service's domain. Usernames often contain both upper-case and lower-case letters and may contain numbers, underscores, or periods. Does Case Matter? Mostly No Is firstname.lastname@example.org the same as Recipient@EXAMPLE.com as far as email servers are concerned? The domain name in an email address is case-insensitive, meaning it doesn't matter whether you use upper or lower case. The same applies to usernames, though outdated email servers can misinterpret capitalization in rare cases. For simplicity's sake, the best practice is to use only lower-case letters in a username. Theresa Chiechi / Lifewire Google email addresses ignore the letter case and periods. For example, email@example.com is the same as firstname.lastname@example.org. Help Prevent Email Address 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.Using periods between names or words can make them easier to read and remember. For example, if you create a new Gmail address, it could be better to choose "email@example.com" instead of "firstname.lastname@example.org."Avoid unusual or whimsical spellings whenever possible. You run the risk of contacts forgetting your address if your name is Susan Davis, but your email address is "email@example.com." Creating an email address that makes sense, relates to who you are and is easy to remember could help someone else wonder whether they should use only lower case characters in your email address. Your Message Will Likely Be Delivered Because the case sensitivity of email addresses can create confusion and interoperability problems, most email providers and clients either fix the case if the email address is typed wrong or ignore it. Not many email services or ISPs enforce case sensitive email addresses.