Ahadith mention in detail so many advantages and merits of blessing the Holy Prophet by reciting darud that one can compile a whole book on them, and many learned people have in fact written books on them. One hadith quotes the Holy Prophet as saying that "One sent by my Sustainer came to me and told me that 'Whoever from your ummah sends darud on you once ten good deeds are recorded on his behalf, his ten (minor) sins are pardoned and he is elevated by ten stages" (Sunan Nisai and Musnad Ahmed, AI-targhib li al Mundhari, P.157 volume 3)
And Anas, a companion, has said that the eternally blessed Prophet said that "When my name is mentioned before anyone it is incumbent upon him to, send darud on me, and whosoever sends darud once, Allah sends His Mercy on him ten times (ibid.)
'Me best darud is the darud-e-Ibrahime which is recited in prayers and the briefest is Sallallaho alaihi sallam, the latter also has the same merits as others. It should be noted that when the holy Prophet's exalted name is written, one writes sallallaho alaihi-w-Sallam after it and not salla'am which is insufficient.