In the past month, I've received a huge volume of spam from Sendgrid. They're VERY spammy emails: a phish, several Bitcoin scam sites, an "Elon Musk wants to give you Bitcoin" spam, "Buy Shares in Pot Companies" spam, and penny stock pump-n-dump spam.
Sendgrid has not responded to my complaints at all.
From the looks of the emails, at the very least Sendgrid doesn't enforce double-opt-in for their customers.