Campaign review delay

Campaign review delay

I am evaluating Zoho campaigns for an animal support organization with 500 members.
All that is needed is basic distribution list functionality. I would use my Zoho mail but this is highly limited in terms of number of email sent and recipients etc.
I was surprised to see that outgoing emails are manually reviewed. This is a concern for us as some of the emails are very urgent .e.g 'dog is lost'. And any significant delay i.e. more than 15mins is a problem.

What is maximum delay for a review? How many campaigns emails before you are whitelisted?

Thanks,
James