HOWTO: Error: 550 'Requested action not taken: mailbox unavailable or not local' when running Plesk

SYMPTOMS

When sending messages through MailEnable the following error is returned in the client:

550 Requested action not taken: mailbox unavailable or not local

Mailbox/es are unable to send and receive.

This article only applies to servers running the Plesk Control Panel and can occur with all mailboxes on the system or only one/some

CAUSE

The Plesk control system has the ability to disable mailboxes within its interface.  To do this the panel edits the MailEnable configuration file (address-map.tab) and adds a ! into the mailbox address which makes the mailbox unrecognisable by the MailEnable services.

To verify this is the case, check in the MailEnable Administration program for a mailbox that is experiencing the issue and see if the mailbox is disabled.  A mailbox that is disabled within MailEnable will have a red cross on the mailbox icon.

For more advanced users, or to verify if Plesk was the service that disabled the mailbox, open the following configuration file;

Program FilesMailEnableConfigAddress-map.tab

and search for any mailboxes that appear like the following entry:

[!SMTP:email@sample.com] a normal mailbox would appear without the ! before the SMTP: part of the configuration string.

RESOLUTION

To resolve this issue, re-enable all the mailboxes within the Plesk control panel, or search through the address-map.tab file and remove all ! characters.