Q: What is the ruling on saying, “Mubarak Ramadan” and “Every year you are well” is this from the Sunnah or not?
A: Shaykh Muhammad b. Saalih al-Uthaimeen rahimahullaah said:
There is no harm in this and this is from the well-known interactions (amongst people) from supplicating for each other. Some of the scholars have mentioned that the Prophet sallallaahu ‘alaihi wa sallam would send glad tidings of Ramadan to his Companions. He would say “Ramadan has come upon you” [Musnad Ahmed and Sunan al-Nisaa’i]. And better than saying, “Every year you are well” is saying, “May Allaah bless you in this month” and “May Allaah aid you in being obedient in it.”
Fataawa page 20 from Liqaa’at al-Ramadhaaniyyah