Does the Post Office at 120 E Grubb Dr, Mesquite, TX 75149 has a mailbox outside the building where I can drop off mail before normal business hours? If so, where is it located at? Thank you.

This location has the lobby (not the in-person mailing office) open during hours not in operation to drop off mail or packages inside. You can even buy postage at the automated drop-box. The machine gives you prompts and options, weighs the item, explains how to measure a package, and shows you what the postage will cost to ship any item with several options, first class, priority, etc. I learned of it not too long ago, and it's nice they have this technology now. Hope that helps.

Yes, when u go into the parking lot make a right