If you send the motion via mail, send it certified mail return receipt requested so you have a record the other parent received the motion. (info.legalzoom.com)
-- I have noticed that some prefer to just mail return shipping labels and / or packaging. (convertmydiapers.com)
They have free shipping to you for orders over $ 50 and I believe now all mailed returns are also free — so, some hassle but at least not too pricey. (corporettemoms.com)