Tool to send email product updates

We regularly send product updates to our users. These go out to 100k people - and happen on email.

In the old days, we would do this using Intercom - but that became impossible. Their pricing is based on number active users, and users are active for 90 days if they get an email from us. We don't want to reactivate all users regularly as this would increase our Intercom bill by many thousands of dollars per month.

We then looked at Mailchimp. First of all it is a pretty annoying product to use. Secondly, it also seems to hit the Promotion tab for most users.

Does anyone have/use a good tool to send regular emails to a lot of users. This is not marketing emails, but also not purely transactional. Preferably we can use Zapier to pipe people from something like Intercom into the tool, and it would take care of deliverability for us (we don't want to hook it up to our own mailserver if we can avoid it).