@Armel, I understand your need to mail a check for deposit into your USAA bank account. You can mail the check to:
USAA Federal Savings Bank
Attn: Bank Priority Mail 9861
10750 McDermott Freeway
San Antonio TX 78284-8426
Be sure to include a deposit slip with the mailed deposit.
You also have the option to order postage-paid deposit envelopes by following these steps:
I hope this helps! ~DC