No. Email addresses are not case sensitive. Having letters in all lowercase makes the email address easier to read, but the oversight won't stop your messages from being delivered.

Do capital letters matter in email addresses Gmail?

Gmail addresses are not case sensitive, meaning the email service doesn't distinguish between versions of the address with or without capitalized letters, so long as the spelling is the same. Similarly, Gmail addresses will still function if you add dots within the username portion of the address.

Does it matter capitals in an email?

Do not use ALL capital letters to emphasize or highlight your message. This is considered to be rude, and can be interpreted as shouting at someone in terms of email etiquette. Use diplomatic language. Write the email when you have time to think and carefully choose your words.