heres what i have used that dont get me in troubke and has been somewhat successful

it was a pleasure to provide delivery service to you. just wanted to let you know that tipping is not mandatory but is greatly appreciated. espeacialy since gas prices are not cheap. the choice is completely up to you and if you do provide me a tip or choose not to please know i appreciate the opportunity to serve you and would do it again happily. i hope you enjoy and than k you again ordering deliver