Just so, what is the most secure way to send mail?
Registered Mail
Similarly, why would someone send a certified letter? The purpose of certified mail is twofold: It creates additional security for a package or letter while it is in transit, and it provides senders with proof that they mailed something. By sending a certified letter, the sender can document making a good-faith effort to get in touch.
Keeping this in view, should I be worried about certified mail?
Keep in mind, certified mail is not always scary. Sometimes a person or business just wants to know that mail is getting to the recipient. It is comforting to send mail that gets received. Even if you reject your certified mail, it can still be taken into legal action that it was attempted to be delivered.
Does certified mail mean something bad?
Bottom Line – Certified mail means that somebody or some business or government agency has something important for you to receive. If it's bad news, refusing the certified mail will not make it go away.