Mass (subscription - non-spam) email sending solution
I have Googled and checked various options. SendGrid looks like the least bad for now.
But would value advice from the more experienced.
I need "a tool" capable of sending hundreds of thousands of emails from time to time, using an application (API).
No, it's not spam - all to subscribed (double opt-in) customers.
Depending on hourly sending limits, it would be good to be able to get some "feedback" to the application when the limit is reached, so it can re-try in an hour.
Paying per email (or 1000 emails) is fine, as long as some sort of cap/limit can be set (just in case, to control the expenses).
Some sort of feedback to the application, with emails that are blocked/bounced would be perfect - to check back with customers on a "working" email address where they can be reached.
Important note (I think):
There is no pre-set, pre-created email list. It changes, list of recipients gets created by an application (like: payment reminders depending on subscription expiry, meeting re-schedules, depending on the assigned courses etc.).
Hope I've properly explained what I'm looking for. Any help, or advice is welcome. Thanks in advance.