So, if you are confident that it's being deposited into an account of the payee at your bank, you don't need an indorsement.
I strongly recommend, however, that your bank require full indorsements including "Mobile deposit to [NAME OF BANK]" to accept a check via mobile deposit. Even here, if the indorsement doesn't include the payee's signature, Article 4-205 of the UCC still says your bank is warranting that the proper party got the funds.
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John S. Burnett
BankersOnline.com
Fighting for Compliance since 1976
Bankers' Threads User #8