All 3 Uses of

correspond
in
The Fountainhead

He came to his office every two or three days; he read the copies of correspondence left in his letter basket according to custom; he sat at his desk and drew flowers on a clean pad; then he went home.
Chpt 1.14 *

correspondence = written letters

Lancelot Clokey, the foreign correspondent, reached for his highball glass and finished it off.
Chpt 3.6 *

correspondent = reporter

What satisfaction is there for a correspondent in reporting on world events?
Chpt 3.6

Definitions:

(1) (correspond as in: corresponding time period)
connect or fit together by being equivalent, proportionate, or matched

(Two things are equivalent if they have the same or very similar value, purpose, or result.)
(2) (correspond as in: corresponding by email)
communicate -- typically by writing letters or email

A corresponding secretary is an officer of an organization who is responsible for managing the organization's correspondence and keeping a record of it.
(3) (correspondence as in: a correspondence course)
done from afar

For example, a corresponding member or a correspondence course.

This sense of corresponding arose because people who lived in distant cities and could not be present for meetings, could communicate by sending written communications.
(4) (correspondent as in: foreign correspondent of the paper)
a reporter or other representative -- typically from a foreign country or with a particular expertise