• The Umbrella hitmaker is said to have been the target of X-rated messages in the post from one mystery man.

And her rumoured boyfriend – baseball player Matt Kemp – is so worried about the situation, he’s advised the singer to be wary of any mail she receives, according to Britain’s Daily Star.

A source tells the publication, “Matt has asked Rihanna’s team to be extra cautious since she was sent two very steamy letters.

“Her friends are also concerned about the situation. They spent ages talking about it when they dined at the Spanish Kitchen in West Hollywood last week. They are really worried things with this guy are going to get out of hand.”

• In other news, RiRi’s ex bf Chris has trouble finding a party avenue for his 21st birthday in New York, Las Vegas or Miami. His people seem to not know that Rihanna is going to be on tour in UK at that time.

A source told the New York Post newspaper:  “They don’t want to mess up their relationship, or their potential relationship with Rihanna.”

Now Chris and his people are planning to have the bash at a private home. Last time they spent his birthday was in 2008 back in Chris’ hometown Virginia.

• Hollywoodlife reports:

“Rihanna celebrated her amazing Kids’ Choice Awards performance March 27 with a trip to Bar 210 at the Beverly Hilton in Los Angeles — but it wasn’t all champagne and laughs. A source at the bar tells HollywoodLife.com that Rihanna’s bodyguard got into an altercation with a yet-to-be-identified man at around 1 a.m. PT and ended up hitting him! Our source, who says Katy Perry was also at the bar, tells us the cops were called and people were told to leave. We reached out to an employee at the Beverly Hilton, who informed us that the man who got hit was actually a stalker, and RiRi’s bodyguard stepped in to protect her. What a scary situation!

We spoke with the Beverly Hills Police Department, who confirmed that a fight did take place March 27 at Bar 210, and that people were asked to leave in order to ensure everyone’s safety.”

• Rihanna’s dancer Byan Tanaka messages the Brazilian Rihanna fans.

I’m in the the last couple weeks of tour production rehearsals with Rihanna and all I can say is “EVERYONE BE READY!!!!” The show is going to be so amazing! Rihanna is looking hot as ever and she’s focused. She’s in rehearsals working hard and sweating right there with us. The process has been really physical and grueling but the results have been great. It feels absolutely amazing to be working with her again. She still is the fun, feisty, down to earth girl I knew from 4 years ago. I’m very happy and lucky to be working with her again. I can’t wait for the world to see the production Rihanna is putting together.
As she would say, “The Wait is Over…The Wait is Over!”