I quite like the idea of being asked if I want to opt out of Mothering Sunday (its real name) emails. There is just something about it that can cause hurt. For some years I would try and turn my face away from card shops emblazoned with encouragement to honour my mother, it was like a knife in the wound now that I no longer had one. Not so much is made of Father's Day, it doesn't have the history behind it, but I accept it might still cause upset to some.
My own mother would always send me a card on Mothering Sunday once I had children, with 'from one mum to another' inside. I used to think it was daft. But I remembered and I now buy cards for my three DiLs and DD, and put the same message in. I am sure they think I am quite mad, but it means that I can now go into card shops (or could!) with a purpose and no longer have to avert my eyes.
As others have said it must be hard for a large number of people, not just the bereaved, but those who have suffered miscarriages, lost children, or are unable to conceive. For years now the Church offers small bunches of daffodils to anyone who would like a bunch on Mothering Sunday, instead of just mothers as it used to, there is no discrimination.