I hate rebates.
I ordered 6 things with rebates from newegg. Four were processed by Newegg. They took 3~4 months but I got 3 back. Still waiting on 1. The other two were other companies for a Raidmax case and a Sapphire card. I haven't had problems before but those two were "lost" in the mail and I never got paid. Complete bullshit. I'm staying away from rebates from now on.
Just b/c it was lost in the mail doesn't mean you are not going to get paid. If you made copies of what you sent, then you should be okay as they should allow you to send in the proof of what you mailed them.
Make copies of what you send in, keep track of it using a spreadsheet and remember to follow up or cross it out when you get paid. See my signature for the spreadsheet.