A few people mentionned having deliverability issues. I am always testing and experimenting to see what works best NOW. quickmail.io + microsoft 365 works the best. I am running 2 campaigns with this set-up at the moment, one gets 53.69% open rate and the other one gets 55.53%. The first one gets 12.08% reply rate The second one gets 0,54% (I have been lazy, it's a list segmenting issue more than anything else) Here is the process: Step 1) Buy several domain names Step 2) Create 2 Microsoft 365 email addresses per domain Step 3) Warm up each addresses for 3 weeks Step 4) Start slowly - 30 to 40 emails per inbox per day (they will likely block you at first, you just need to unblock it and start again slowly) I would not exceed 10 domains per Microsoft instance, and pay with a different credit card when you open a new one. Plug those inboxes into Quickmail, Success, Smartlead, Instantly or esle (this doesn't really make a difference) That's it. Very Simple. You can configure the DNS directly from the registar (I use internetbs), don't even need a server or anything. The only downside... Microsoft 365 inboxes are not free.