811 Main tenants are issued a designated mail box in the postal area in the tunnel, Level B-1. The number of the box is for designation purposes only and is not a "post office box" number to be used for mailing purposes.
Your mail is appropriately addressed if the following building address is used:
811 Main Street, Suite #
Houston, Texas 77002
The Mailroom also houses drop-boxes for FedEx and UPS. Please visit their websites for information on services offered.