いては
tsuitewa

Conjunction

1. in line with this; therefore; consequently; so; such being the case; in that regard; in this connection

Usually Written in Kana
ついては、私 わたくし手紙 てがみのコピーを添付 てんぷいたします。
tsuitewa watashino tegamino kopiio tempu itashimasu
I am sending a copy of my letter to you.