the text on the stamp is in blue below

Translated by Chandra Rajan

The impassioned lover having passed some months
on that hill, parted from her, unsupported
-the golden armlet slipping down
to lay bare his wasted forearm
saw on the Ashadh's most auspicious day
a cloud embracing the crest of the hill
strikingly-shaped like a sporting elephant
bent down to butt a river bank
... he made with reverence
an offering of fresh blossoms of wild jasmine

Stamp from Rahul's collection

Complete Meghadutam text itrans devanagari (postscript), translation