kind regards

be cruel to be kind

To act cruelly in order to achieve a positive outcome in the future.

best regards

Used as a polite closing of a letter

in kind

In a reciprocal manner; in a similar way; in the same kind.

kind of

Slightly; somewhat; sort of.

kindest regards

Used as a polite closing of a letter

warm regards

Used as a polite way to finish a letter.

warmest regards

Used as a polite closing of a letter