In the thousands of posts I have read on this and other legal sites, I have never heard of a warrant being sent to anybody, certified or regular mail. I would bet that it is a notice to appear in court and by sending it certified, they are making sure you receive it. Probably a lot cheaper than using a process server. Ignoring it won't make it go away either, the police and courts are smart enough to know that many people will think that way.
If you feel my answer is rude, mean, snarky or in anyway not to your liking, I did my job. You don't need to tell me.
No private messages, I do not reply to them.