Are you using MS Outlook application? And use POP3 account for receiving and sending emails. Sometimes, your Outlook PST file get crashed or damaged due to damaged POP3 server, account setting incorrect, no connection to the network etc. After that you receive Outlook error messages on screen:

“The operation timed out waiting for a response from the receiving (POP) server 0x8004210a”

Outlook professionals fix this error with Outlook PST recovery software, which fix error 0x8004210a messages, fix unread emails, fix distribution member list, fix protected emails etc. Outlook Recovery software recover data and fix error from Outlook PST file (ANSI and UNICODE file). Trial edition of PST recovery tool able to fix error 0x8004210a and gets recovered Outlook items. Complete Outlook recovery software only ay $49 and also split large Outlook PST. Click here to know more details: http://www.outlook.pstrecovery.us/fix-error-0x8004210a-in-outlook2007/