0x8004210E error generally pops out whenever user tries to open up their email account or want to send or receive their mails via configured Outlook accounts and their mail account gets blocked with the message like: -
"Task - Receiving' reported error (0x8004210E): 'Your mailbox is temporarily unavailable because another e-mail message is being delivered to it or another mail application is accessing it. The server responded: -ERR box locked"
This is a common mailbox temporarily not available error among the users of Microsoft email clients like Outlook express, windows mail and seems like an serious server error to the common user. The mailbox temporarily not available error message is also sometimes experienced by the users of some other mail clients termed as POP Lock or Box Lock error. 0x8004210E error in Outlook arises due to many reasons and one of the frequent reason for eruption of this error is the mail server which users are attempting to connect have an open connection already to their email account. This generally happens when user is connected to their mail accounts with any other device such as smart phones, wi-fi or through any other accessible medium or in the situation when mail server is not appropriately stopped the lock by the end of POP 3 sessions.
Outlook error 0x8004210E also occurs due to any malformed e-mail message send over the user's account. Some other reason for the occurrence of Pop Lock 0x8004210E error message is virus corruption or due to the anti-virus application which sometimes blocks your incoming Outlook mails resulting in the error. Using more than one mail client is another reason for this error message over your monitor screen. Larger attachments and increase size of PST or PST corruption also results in Outlook error 0x8004210E. In order to fix 0x8004210E error, user need to follow the following steps: -
- Don't use more than one mail clients or disable them before using your Outlook mail account.
- Remove the larger unused mail attachments.
- Disable your anti-virus application. Email message incoming is sometimes blocked by the anti virus software of your PC. Disabling the anti-virus fixes the problem. After the issue is solved enable anti-virus.
Still you are unable to access your Outlook mail accounts then you may try fixing the 0x8004210E error issue with the help of Outlook Inbox repair tool. This tool is capable of fixing POP Lock error in Outlooks. But sometimes Inbox repair tool fails to correct Outlook error if it had arose due to increased PST size of PST corruption. In such case you may try solving the error with the help of PST Inbox repair software which repairs entire Outlook error and fixes PST corruption and finally restores your Outlook mailbox by fixing Outlook error 0x8004210E.