Invalid Email Account

If you get error 550 (or 554, depending on the recipient’s email server), it means that the email address you are sending the message to does not exist.

Example of messages associated with this error:

550 [email] User unknown

550 Sorry, no mailbox here by that name. (#5.1.1)

550 Requested action not taken: mailbox unavailable

550 5.1.1 [email] is not a valid mailbox

550 No Such User Here

550 Invalid recipient

[email] (user not found)

5.1.0 – Unknown address error 550-‘MAILBOX NOT FOUND’

550-5.1.1 The email account that you tried to reach does not exist.

550 5.1.1 [e-mail]: Recipient address rejected: User unknown in relay recipient table

554 delivery error: This user doesn’t have a [name of the service] account

554 delivery error: Sorry your message to [email] cannot be delivered. This account has been disabled or discontinued

550 #5.1.0 Address rejected [email]

A message that is related to the same problem we are describing is this one, where the recipient’s host (i.e., email server) doesn’t exist:

Sorry, I couldn’t find any host named [host]. (#5.1.2)

If you got the email address from a real person, most likely there is a typo somewhere. Double check the email address you typed. If you obtained the address by phone, you may have misheard the name or a letter and ended up writing down the wrong email address.

However, if you obtained the recipient’s email from a website, from a magazine, an advertisement, etcetera, and you double-checked it to make sure there is no typo, this means that the email simply doesn’t exist. We know how frustrating this may be, but there is nothing we can do about it!


Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.