postmaster

n. manager of a post office; mail manager, person responsible for managing electronic mail on a network (Computers)

For other things named postmaster, see Postmaster (disambiguation). Postmaster (or Postmistress) refers to the head of an individual post office. When a postmaster is responsible for an entire mail distribution organization (usually sponsored by a national government), the title of Postmaster General is commonly used.
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Noun
1. the person in charge of a post office
(hypernym) master
(hyponym) postmistress

(n.)
One who has charge of a station for the accommodation of travelers; one who supplies post horses.
  

(n.)
One who has charge of a post office, and the distribution and forwarding of mails.
  

The electronic mail contact and maintenance person at a site connected to the Internet or UUCPNET. Often, but not always, the same as the admin. The Internet standard for electronic mail (RFC 822) requires each machine to have a "postmaster" address; usually it is aliased to this person. See also webmaster.