Originally Posted by cwc

Yes, you will earn miles .

If the ticket is booked this way.

1. Use AE travel website
2. Pay with an AE card
3. Also, during check-out choose to use AE MR point as payment method (for part or whole amount)
4. The payment will 1st charge to your credit card and then MR will be deducted from MR account. A credit will be issued to the credit card later.

So in UA point of view, you paid with your AE credit card, and it is a "normal" ticket (Oh, depend on your status & class fare, you can also upgrade and get bonus miles) but actually it is a MR point "award" ticket.

BUT!!! You said it is a corporate account! I don't think you can get the ticket!

FROM AE website:
To redeem points for travel, the American Express® Card account you select for the transaction must be enrolled in the Membership Rewards program and all your Card accounts with us must be in good standing. You may not use a Corporate Card account for this transaction. You must also be the basic Cardmember of the Membership Rewards account.