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How to fix “550 Requested action not taken: mailbox unavailable or not local” in Plesk servers

How to fix “550 Requested action not taken: mailbox unavailable or not local” in Plesk servers

Mail errors are commonly encountered issues in our role as Website support specialists. In Plesk Windows servers, the default mail server is MailEnable.

Plesk account owners sometimes report the MailEnable error ‘SMTP server response: 550 Requested action not taken: mailbox unavailable or not local’ when trying to send out mails or when managing their account functions through the Plesk panel.

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What does this error mean?

The error denotes that MailEnable found the recipient domain of a mail in the server, but couldn’t locate the email username. For example, let’s say MailEnable received a mail to be delivered to “”.

It would look for active mail services for “”, and then for the inbox of “mail-recipient”. If it is able to locate “”, but not “”, this error would be returned.

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Why does this happen?

We have noted the following situations in which this error is reported by Plesk panel accounts.

1. For some unknown reason, when the recipient mailbox was disabled by the account owner, or because of a bug in Plesk.
2. When the email account is hosted elsewhere (like Google Apps), but the domain has mail services enabled in the local server.

Bonus tip : If the customer receives this error (as shown below) while using the Plesk panel, it means that the administrator email for the domain is set to an email account which is either disabled in the local server, or is hosted elsewhere.

Warning: Unable to send notification: mail() failed: mail() [function.mail]: SMTP server response: 550Requested action not taken: mailbox unavailable or not local

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How to fix this error?

1. If the email service for the domain is hosted elsewhere, just turn off mail services by going to:

Domains > Mail > Disable Mail

2. If the MX points to the local server, check if the email account is disabled, and if so, re-enable it.

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Mail service is perhaps the most important online service that aids day-to-day business transactions. A contract that needs to be signed, a quote that needs to be sent, market trend data that needs to be presented – none of these can wait – We know!

That is why Bobcares engineers give high priority in resolving email errors. We use server logs, user reports and test routines to quickly identify the cause of mail errors, and fix them in as little as 10 minutes.

If you’d like to know how you can better support your mail users, we’d be happy to talk to you.


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  1. I get ‘550 5.5.0 Requested action not taken: mailbox unavailable.’ only when I type the recipient’s address into the address box. If their address is already in my address book, there is no problem. I have windows 10, Thunderbird, TalkTalk.

    • Kit,

      This could be due to some misconfiguration that is preventing mail delivery to new addresses. Please submit the details of your issue at and our server specialists would fix it in no time.

  2. we are getting following error when i send to my domain to another domain below error getting.

    please guide me

    Your message did not reach some or all of the intended recipients.

    Subject: test email from ict
    Sent: 1/5/2018 6:12 PM

    The following recipient(s) cannot be reached:

    ‘’ on 1/5/2018 6:12 PM
    Server error: ‘550 Requested action not taken: mailbox unavailable or not local.’

    • Nataraj,

      The issue could be related to the recipient mail address. Please contact our support team at if you still face issues. They’d help you resolve it.

  3. Thanks, I’ve disabled mail service in receiver domain as its already hosted on Gsuite. Its really worked for me!


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