I have read the previous posts regarding this error, including the one started by I JYoung on May 19, 2014, and apparently resolved for that user on May 30, 2014 by Cesar_E. Unfortunately, the solution appears to have involved changes made to the accounts by Cesar_E, and I do not know what those changes are and am guessing that I'd probably be unable to implement them if I did.
As background, please note that I am running Windows Live Mail 2012 on Windows 7. I am having problems with two email accounts, both receiving the above-referenced error message. I have tried the fixes suggested (removing and reconfiguring the account, checked the Outbox, etc) with no success. I am running Norton AV software, and have tried turning off the e-mail protection, again without any success. The problem does notalways occur, but does occur more often than not: I would estimate approximately 90% of the time.
I further note that my husband is running Windows Live Mail 2011 on Windows 7 on a different machine, and is not encountering this problem with these accounts.
Can someone offer some help to eliminate this problem?