All 6 Uses of

correspond

in

The Three Musketeers

The cardinal sets a spy upon a gentleman, has his letters stolen from him by means of a traitor, a brigand, a rascal-has, with the help of this spy and thanks to this correspondence, Chalais's throat cut, under the stupid pretext that he wanted to kill the king and marry Monsieur to the queen!
Chpt 2.

correspondence = written letters

Porthos comprehended that this chest, although it did not correspond in shape with that which he had seen in his dreams, must be the blessed coffer, and he congratulated himself that the reality was several feet higher than the dream.
Chpt 32. *

correspond = fit together

She is to correspond with nobody; she is to speak to no one but you—if you will do her the honor to address a word to her.
Chpt 50. *

correspond = exchange letters through the mail

But when the cardinal added that not only Mme. de Chevreuse had been in Paris, but still further, that the queen had renewed with her one of those mysterious correspondences which at that time was named a CABAL; when he affirmed that he, the cardinal, was about to unravel the most closely twisted thread of this intrigue; that at the moment of arresting in the very act, with all the proofs about her, the queen's emissary to the exiled duchess, a Musketeer had dared to interrupt the course of justice violently, b†
Chpt 15.

But they have corresponded; it is to him that the queen has been writing all the day.†
Chpt 16.

You are charged with having corresponded with the enemies of the kingdom; you are charged with having surprised state secrets; you are charged with having tried to thwart the plans of your general.†
Chpt 67.

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
(5) (meaning too rare to warrant focus)