Google's Gmail Web-based email service runs on the Internet Message Access Protocol system, but it also offers Post Office Protocol mail server access.
Definition of LUMEN. 1. 2. : the bore of a tube (as of a hollow needle or catheter). 3. : a unit of luminous flux equal to the light emitted in a unit solid angle by a uniform point source of one candle intensity.
lumen The inside of any tube, such as a blood vessel, an air passage (bronchus) or the intestine. lumen any cavity enclosed within a cell, or structure, such as the lumen of the gut. Lumen