If you are out of the area or just can’t drop the racket off then use the Postal Service.
If using this service please ensure you package up the racket(s) securely and use a reliable/secure method of postage. I have used Hermes in the past which have been reliable, offer insurance and tracking options for a reasonable price. They also pick up from your house. You can sign up through their website.
I won’t charge for the return postage contribution if more than 2 rackets are needed to be strung.