Later on, we upgraded to Pro Plan and received a fresh IP (no warmup). Our deliverability struggled because of low sending volume and IP was present on some public blacklists. Same templates went to spam on Outlook (tried changing the wording etc)
Decided to downgrade the plan, as we're getting more customers and onboarding email is a crucial part of the experience.
Now we got assigned to another IP pool, but ALL our emails bounce from Outlook (with the message that part of the providers network is blacklisted) and do not even reach spam...
I've submitted a support ticket, but it's gonna take a few days to get reply + most likely they're going to advertise selecting a more expensive plan with dedicated IP (spam better than bounce but it's still horrible before we have IP warmed up).
Is there a better provider with high volume shared IP or a quick way to solve this problem?
You could try your own VPS and mail in a box. But you run the same risks.