Hello.
Nice to meet you.
This is Cristian.
While reading your job description carefully, understand you're looking for a developer who have much experience in mailgun for send the 300k emails per month completely.
This is interesting and I've best solution to fix it.
Originally, we can't send the much mail in one time.
But in my experience, we need to use mailgun for this project.
I hope we can have an interview with this project.
Thanks.