'mail call' definitions:

Definition of 'mail call'

(from WordNet)
noun
A call of names of those receiving mail

Definition of 'mail call'

From: GCIDE
  • mail call \mail call\ n. A call of the names of those persons receiving mail for the purpose of transmitting mail to them; -- a technique used in the military services to deliver mail to enlisted personnel. [WordNet 1.5 +PJC]