Is direct mail legal? (Central Illinois)

[Jacob Lindgren]

I apologize for the clickbait, but it does encapsulate my anxiety. 

My plan: 

Drive around my target area.

Write down addresses of homes I would be interested in (unkept yard, abandoned, etc.)

Send one hand written letter that simply states that I would be interested in purchasing their home and to let me know if they would be interested. I planned to give my first name and phone number. I also planned to note in the letter that I would only be sending one letter to be respectful. I would not be making any promises to the potential seller such as price or a guarantee offer.  

The issue:

I thought this was the a run-of-the-mill plan and had no anxiety about it. I then considered that I don't want to do it without speaking to my attorney in case there are any harassment laws I could be tripping over. 

The discussion with my attorney didn't go well. They just said it's better not to do it. They didn't state a specific reason not to do it, just that you don't want to open yourself up to potential harassment issues. I want to take sound advice and not just ask around until I get the answer I'm looking for. That being said this strategy is pretty run of the mill in RE investment circles so I have a hard time thinking its a bad idea.

What do you guys suggest? I would hope one hand written letter would not cause me a headache.

Thank you in advance.