この間郵便受けに入れといた歌詞どうかな

[Yoku iu yo]

この間郵便受けに入れといた歌詞どうかな

Can someone help translate the underline part for me? The translation I have is (what do you think of the lyrics I put in your mailbox).

 

[Glenn]

It's a contraction of 入れておいた.

 

[Yoku iu yo]

Alright, thanks.