Getting Error message while record is created through inbound email

Scenarion to understand: lets say 5 emails of same format sent to salesforce address, 3 got created and 2 getting Bounced.

The error message i am receving in my mail is

Error Occured: System.ListException: List index out of bounds: 1

And if i check in Debug Log received template at saleforce end is

The Microsoft Exchange Server Mailbox Manager has performed an automated
cleanup of your mailbox.
2 item(s) were deleted from the System Cleanup/Inbox folder.
1 item(s) were moved from the /Inbox folder to the System Cleanup folder.

For additional information contact your Business Help Desk.

Can some one Help me in Resolving this.

Thanks in Advance