sincere

a. 真诚的,诚挚的

Please give my sincere regards to all the members of your family.

请向你全家转达我真挚的问候。

Sincere congratulations on your son wedding please convey our best wish.

令郎喜结良缘谨此致以诚挚的祝贺并请转达最美好的祝愿。