SMTP Code 550

The transaction failed permanently. The server will not try to send the message again. This is used as a general error code, so there are many reasons why you could be seeing it.

It’s common for email service providers to add a status code (5.1.1) after the SMTP reply code (smtp;550) for additional categorization of the issue.

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Email service providers

AT&TAll AT&T codes →

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smtp;550 5.2.1 <EXAMPLE@PRODIGY.NET>... Addressee unknown, relay=[x.xx.xx.xx]

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smtp;550 5.2.1 <example@prodigy.net>... blank mailhost - invalid address, relay=[x.xx.xx.xx]

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smtp;550 5.7.1 Connections not accepted from servers without a valid sender example.com. Fix reverse DNS for x.xx.xx.xx

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ComcastAll Comcast codes →

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smtp;550 5.1.1 Not our Customer

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smtp;550 5.1.1 <example@comcast.net> recipient mailbox unallocated

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smtp;550 5.2.0 Message rejected due to DMARC. Please see http://postmaster.comcast.net/smtp-error-codes.php#DM000001

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GmailAll Gmail codes →

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smtp;550 5.1.1 The email account that you tried to reach does not exist. Please try double-checking the recipient's email address for typos or unnecessary spaces. Learn more at https://support.google.com/mail/?p=NoSuchUser - gsmtp

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smtp;550 5.2.1 The email account that you tried to reach is disabled. Learn more at https://support.google.com/mail/?p=DisabledUser - gsmtp

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smtp;550 5.2.1 The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. For more information, please visit https://support.google.com/mail/?p=ReceivingRatePerm - gsmtp

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smtp;550 5.7.1 [x.xx.xx.xx] Our system has detected that this message is likely suspicious due to the very low reputation of the sending domain. To best protect our users from spam, the message has been blocked. Please visit https://support.google.com/mail/answer/188131 for more information. - gsmtp

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smtp;550 5.7.1 Unauthenticated email from example.com is not accepted due to domain's DMARC policy. Please contact the administrator of example.com domain if this was a legitimate mail. Please visit https://support.google.com/mail/answer/2451690 to learn about the DMARC initiative. - gsmtp

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iCloudAll iCloud codes →

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smtp;550 5.1.1 <example@icloud.com>: user does not exist

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smtp;550 5.7.1 [CS01] Message rejected due to local policy. Please visit https://support.apple.com/en-us/HT204137

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smtp;550 5.7.1 Your message was rejected due to reservation-example.com’s DMARC policy. See https://support.apple.com/en-us/HT204137 for info

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smtp;550 5.7.1 Your email was rejected due to having a domain present in the Spamhaus DBL -- see https://www.spamhaus.org/dbl/

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Mail.ruAll Mail.ru codes →

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smtp;550 Message was not accepted -- invalid mailbox. Local mailbox example@mail.ru is unavailable: account is disabled

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smtp;550 spam message rejected. Please visit http://help.mail.ru/notspam-support/id?c=7y4ytdHbuOGv3O50NYTwpz1F-TVIpnactxtFPeFQSDYMAAAAaKgAAOX_3hE~ or report details to abuse@corp.mail.ru. Error code: B5322EEFE1B8DBD174EEDCAFA7F0843535F9453D9C76A6483D451BB7364850E1. ID: #

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smtp;550 Message was not accepted -- invalid mailbox. Local mailbox example@mail.ru is unavailable: account is disabled

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OutlookAll Outlook codes →

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smtp;550 5.5.0 Requested action not taken: mailbox unavailable. [#.eop-nam12.prod.protection.outlook.com]

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smtp;550 5.7.1 Service unavailable, MailFrom domain is listed in Spamhaus. To request removal from this list see https://www.spamhaus.org/query/lookup/ (S8002) [#.eop-nam02.prod.protection.outlook.com]

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smtp;550 5.7.1 Unfortunately, messages from [x.xx.xx.xx] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [#.eop-nam02.prod.protection.outlook.com]

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smtp;550 5.4.1 All recipient addresses rejected : Access denied [#.eop-nam02.prod.protection.outlook.com]

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VerizonAll Verizon codes →

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smtp;550 relaying denied for <example@example.com>

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YandexAll Yandex codes →

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smtp;550 5.7.1 Policy rejection on the target address

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smtp;550 5.7.1 No such user!

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smtp;550 5.7.1 Email rejected per DMARC policy for mail.ru #

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ZohoAll Zoho codes →

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smtp;550 5.7.1 Email rejected per DMARC policy for zoho.com

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smtp;550 5.1.1 <example@zoho.com> User unknown

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Spam filters services

BarracudaAll Barracuda codes →

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smtp;550 cuda_nsu 5.1.1 <email@example.com>... User unknown

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smtp;550 No such user (email@example.com)

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smtp;550 Blocked

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smtp;550 rejecting spoofed message

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smtp;550 cuda_nsu 5.4.1 [email@example.com]: Recipient address rejected: Access denied [example.com]

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MimecastAll Mimecast codes →

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smtp;550 Administrative prohibition - envelope blocked - https://community.mimecast.com/docs/DOC-1369#550 [#]

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smtp;550 Rejected by header based Anti-Spoofing policy: email@example.com - https://community.mimecast.com/docs/DOC-1369#550 [#]

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smtp;550 Rejected by header based manually Blocked Senders: email@example.com - https://community.mimecast.com/docs/DOC-1369#550 [#]

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smtp;550 Envelope blocked - User Entry - https://community.mimecast.com/docs/DOC-1369#550 [#]

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smtp;550 DMARC Sender Invalid - envelope rejected - https://community.mimecast.com/docs/DOC-1369#550 [#]

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Office 365All Office 365 codes →

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smtp;550 5.4.1 [email@example.com]: Recipient address rejected: Access denied [example.com]

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smtp;550 5.7.1 Service unavailable, Client host [x.xx.xx.xx] blocked using Spamhaus. To request removal from this list see https://www.spamhaus.org/query/ip/0.0.0.0 (AS16012611)

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550 5.7.1 Service unavailable, Helo domain is listed in Spamhaus. To request removal from this list see https://www.spamhaus.org/query/lookup/ (S8001) [#.prod.protection.outlook.com]

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smtp;550 5.7.606 Access denied, banned sending IP [x.xx.xx.xx]. To request removal from this list please visit https://sender.office.com/ and follow the directions. For more information please go to http://go.microsoft.com/fwlink/?LinkID=526655 (AS16012609)

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ProofpointAll Proofpoint codes →

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smtp;550 5.1.1 <email@example>: Recipient address rejected: User unknown

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smtp;550 5.1.1 <email@example.com>: Recipient address rejected: undeliverable address: host example.com[x.xx.xx.xx] said: 550 5.1.1 <email@example.com>: Recipient address rejected: undeliverable address: host example.com[x.xx.xx.xx]

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smtp;550 5.1.1 User Unknown

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smtp;550 5.1.1 - This is not a valid email address. Please verify that you have the correct email address for your recipient.

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smtp;550 5.7.1 <email@example.com>: Recipient address rejected: User email address is marked as invalid.

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smtp;550 5.7.1 Relaying denied

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SymantecAll Symantec codes →

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smtp;550 Invalid recipient <email@example.com> (#5.1.1)

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Other SMTP codes