Earlier quoted context omitted.
Hopefully not since 2003 when the FTC had a court enjoin that specific company from making misleading statements about renewals in their postal mail. The mails they send out now look like this: "As a courtesy to domain name holders, we are sending you this notification of the domain name registration that is due to expire in the next few months. When you switch to Domain Registry of America, you can take advantage of…
It was past 2003. I think I registered jrock.us in 2004. But yes, they may have mentioned "this is not a bill", but if they did, the font was so small as to be unreadable. I knew it wasn't a bill because I knew that my domain was registered through someone else.
There is print that says "this is not a bill" about 6-10 sentences in, but is hardly discoverable without careful consideration. Considering the whole page is covered by text, most people would skim and think "oh shit I owe money don't I?!"