Insincere

The letter sounds forced, what is worse, insincere.

They say fine words are no virtue if they're insincere and that's him in a nutshell. He's all talk but doesn't mean a word of it.

Everyone loves to hear praise, but over-praise has the opposite effect of sounding insincere.

Tom is insincere.

You're insincere.

They're insincere.

Don't force your actions or be insincere; kids can always tell.

One won't profit by an insincere gift.

Tom was insincere.

Tom seems insincere.