Flamsteed's first regular correspondent was John Collins(1625-1683), who corresponded extensively with many mathematicians including Towneley.
However, Galileo was close with Virginia, and they corresponded extensively.
His primary interest was however in birds and on these he corresponded extensively with Edward Blyth.
He corresponded extensively with Einstein on this matter, seeking advice on the various possible candidates.
Wilson was also a friend of Nabokov, with whom he corresponded extensively and whose writing he introduced to Western audiences.
Philip corresponded extensively with him.
Lovecraft and the Eddys corresponded extensively until Lovecraft's mother Susie was taken to the hospital in spring 1919.
Sibley became estranged from his American co-workers for a time and corresponded with overseas colleagues extensively.
From 1932 until his death in 1997, Cave corresponded extensively with fellow pulp writer Carl Richard Jacobi.
He corresponded extensively with many aspiring blacksmiths.