Not addressing an envelope properly to someone
(Bath, Somerset, England )
My stepson and his wife and family always send my mother a birthday card on her birthday as she lives with us. Although this is thoughtful they always address the envelope to ' Shirley ' ' but not her surname despite the fact that I have told them her surname on more than one occasion. This has continued for the past 9 years and although it's kind to send her a card it seems to be really bad manners.
Should I just ignore it even though my mother is offended by it?