Re: Campaign managers, time to use Segwit and require your posters to use it too
Are you sure about this? From what i know both sending and receiving addresses have to be segwit compatible to be considered as segwit transaction with lower size + lower fee. 
I quote this Reddit post: https://www.reddit.com/r/Bitcoin/comments/7l9tda/day_2_i_will_repost_this_guide_daily_until/
Quote
A transaction between two SegWit addresses is a SegWit transaction.
A transaction sent from a SegWit address to a non-SegWit address is a SegWit transaction.
A transaction sent from a non-SegWit address to a SegWit address is NOT a SegWit transaction.
A transaction sent from a SegWit address to a non-SegWit address is a SegWit transaction.
A transaction sent from a non-SegWit address to a SegWit address is NOT a SegWit transaction.
Basically, it counts as a SegWit transaction if the sending address is a SegWit address (either P2SH-P2WPKH or bech32).