Thank You For Thank You to Repeat Customer
Hi {Customer},
Just popping in your inbox real quick to say that we noticed that this is your {third/fifth/etc.} order with us. We know there are plenty of places to buy {item}, so we're really glad you chose to purchase from us again.
If you have any questions or concerns regarding your order, please don't hesitate to drop us a line!
Best,
{Your Name}
{Your Role}