Here are the pickup locations for Logan Airport.

Terminal A
Arrivals for Delta, Delta Shuttle, and Southwest.  (No customs.) Exit the baggage claim level and cross two traffic lanes to meet your driver.
Terminal B
Arrivals for Air Canada, American Airlines, PenAir, Spirit, and United.  (No customs.) On the baggage level, make your way to the parking garage. The limo area is in the middle of the garage.
Terminal C
Arrivals for Aer Lingus, Alaska Airlines, Cape Air, Emirates, JetBlue, Sun County Airlines, and Virgin America.  (No customs.) Use the exit on the upper level. Follow crosswalk to 3rd traffic island to meet your driver. This is one level above the baggage claim.
Terminal E
All international arrivals.  (Customs required.) Exit Door E 104 on the baggage claim level and cross two traffic lanes to meet your driver.