宛てる is read as あてる (ateru) and means to address.
あてる
ateru
あてさき
address
あてな
name and address (on an envelope, etc.)
あてがき
addressee's name and address
あてながき
addressing (e.g. writing an address on an envelope)
あてさきあどれす
destination address
あてどころ
address (of a letter, parcel, etc.)
えんてん
(of eyebrows) shapely
えんぜん
as if
てがみをあてる
to address (direct) a letter to a person
なあてにん
addressee
なあて
address (on an envelope)
わたしあて
addressed to me