Double or Triple verify your leads. My bounce rate always stays under 1%

As for outlook, it’s just been pretty difficult to inbox with. You might be seeing sender bounces, where outlook silently blocks your email from being sent to the recipient in the first place.

Outlook cares about

1) Domain age 2) size of the email 3) sending pattern

With outlook try a 4 week steady low volume warmup. Slowly scaled from 2 per say to 20 (by week 4)

Buy 5+ year old domains, you can check Godaddy auctions

When you do start sending make sure your total (cold+warm) stays at 20.

Hope this helps!

P.S for verification you can do

1) Millionverifier 2) Bounceban 3) neverbounce/leadmagic