It seems there was an issue which is related to the timer jobs getting stopped. 
The incoming emails were not received in time in SharePoint document libraries. 
In fact they got delayed by more than 12 hours. I looked at the ULS logs and I saw that the there was an error
 The previous instance of the timer job 'Microsoft SharePoint Foundation Incoming E-Mail', id '{E10C7C66-8F03-49C0-AB87-108F24469613}'
 for service '{9D74DC32-5B38-4D3F-90CD-237DF430F093}' is still running, so the current instance will be skip

It sounds like there was a stuck timer job.  Do you have Incoming Email configured across multiple servers?

Hi,

i have configured multiple imcoming email .

then i have check timer job stucked . so restard all the server . and check again . my team got a mail after 12 hrs . letter .

Deepesh Yevle,

This is final warning to you. Please DO NOT scratch old threads and post your dumb answer into those threads. I have seen that you have posted a long description in all UPS related threads and all threads are ancient threads. If you want to help people then concentrate to new threads.

Here is one thread where Trevor warned you.

http://social.technet.microsoft.com/Forums/sharepoint/en-US/b7cb578b-a72c-4ca5-bcbf-891ef31e7704/user-profile-service-event-6801-required-attribute-accountname-is-missing#7c97a0c2-4385-4ac2-8f50-d49aad5ca716

If you have anything, which you want to share with us then create new WIKI instead of posting in all threads.

{SP Forum Mode