“The only difference between the two emails was the link,” the memo said. “ActBlue delivered. WinRed got flagged. That is not a coincidence.”
It could also be that winred is more often associated with spam because emails with winred links use a style more associated with other actual spam. Like if spammers use words like Trump a lot to try to scam victims, and a lot of those emails get flagged as spam, then the word Trump itself becomes more highly correlated with spam. And since the word Trump is highly associated with winred links, maybe winred gets caught up in the rule set/heuristics that associate Trump fundraisers with spam.
It could also be that winred is more often associated with spam because emails with winred links use a style more associated with other actual spam. Like if spammers use words like Trump a lot to try to scam victims, and a lot of those emails get flagged as spam, then the word Trump itself becomes more highly correlated with spam. And since the word Trump is highly associated with winred links, maybe winred gets caught up in the rule set/heuristics that associate Trump fundraisers with spam.