Do you know for sure you're on it? Might just be the recent registration time of the subdomain... some mailservers are especially unenthusiastic about novel domain names, even subdomains, and then when they've seen enough mail from them in circulation they calm down a bit.
Do you have a link for applying to get off of protonmail.com's blacklist?
Do you know for sure you're on it? Might just be the recent registration time of the subdomain... some mailservers are especially unenthusiastic about novel domain names, even subdomains, and then when they've seen enough mail from them in circulation they calm down a bit.