How to safely send mail without "substituting" your domain?

Question

gmail

Hey!
The client base (10 thousand emails) remained from the old project.
When launching a new project (potentially interesting to these users), it was decided to send out a mailing list to the database with a story about the benefits of a new project and an offer to join.
We use Sparkpost (to replace Mandrill). SPF, DKIM are configured on the domain. The letter contains a link to unsubscribe (although the letter is one-time).
Conducted a test mailing to 1000 addresses.
Of these, I received about 10-15 "complaints about spam", and about 40-50 invalid addresses (wrongly written, blocked and other addresses).
I don't have much experience in direct marketing. I wondered if I was spoiling the reputation of the new project's domain in this way? After all, it is sending out. I really would not want to lose the trust of postal services because of a one-time mailing.
Tell me, am I doing everything right? Or you need to register a separate domain - and send mail from it, without fear of spoiling the karma of the main domain.

Answer 1

spam in its original form
Make a landing page and collect emails from it

Answer 2

free services do not always work effectively (I didn’t work with www.mailgun.com, so I can’t talk about it)
Try mailchimp - a rather simple and pleasant mailing service with full statistics, you can connect 360 e-commerce and much more.
If memory serves, but they have up to 3000 for free, and then small amounts. Pay $80 for 10,000 mailing addresses

Answer 3

Perhaps non-existent addresses failed. It is better to check the base for validation. Here are the two cheapest email verification services www.emaillistverify.com for 1000 takes 4$ and this deliverbility.com for 10k takes only 5$