[Lorenz-Kraft]

Hi, I'm not really much into SendGrid/Mailchimp and alike, but isn't this their main purpose? Have you tried to contact SendGrid and report your issue? As far as I know, these companies have agreements with each other to NOT BLOCK their manages mail addresses/IPs by default.

[chaoz_]

From my experience, SendGrid support will respond within 2-3 days and there's no guarantee they will agree to rotate the IP pool.

Bounce message clearly says that "part of providers network is on the blacklist".

Wanted to know if there's a solution that worked instantly for "Outlook" for someone.