Is it the user or the technlogy?

So I've come to learn over the past few days that a number of people were not aware of this weekends celebration party. This has been a bit of a blow to me as I had tried to cover my bases with eamils and blog mentions and indirect posts here.
I'm trying to forgive myself because I know my dad would have said "I told them to check their email not my fault if it went to spam" and just have moved on. But for me sometimes it's just not that easy.