Ewing Gillaspy 62% open rates are not bad and blasting to 100K in one shot from one domain is totally fine.
Email deliverability can be fixed with engagement.
Send these two kind of campaigns at least twice a month to see improvements:
- 1.
- 2.
Emails that excite the customer to click or reply back - say a survey, quiz
Also would add the point about not sending to un-engaged subscriber.
Testing current domain health is the easiest part.