Sunroofs have 4 drains. 2 are routed down throughout the A-pillars and 2 are routed down through the rear quarters. Ramon and Sam are correct that the slit drains can clog and back up into the rear quarters. It can back up to the roof speakers if it's bad enough. The fronts can clog and will back up to approximately the A-pillar grab handle - you WILL get drenched when that happens. They'll drip straight down from there right along the edge of the carpet/door jamb trim if the flow is heavy. It'll flow down the A-pillar to the floor if the flow is light.
The drain lines can be chased out with string trimmer line from above and something slimmer from below (like Sam said). Don't use compressed air for fear of disconnecting the drain tubing connections.
There's also 2 plastic front corner pieces in the sunroof track area that can warp slightly and cause leak issues. See johnvees80thread for part numbers and detail. The 2 new pieces are inexpensive.
@GLTHFJ60 -