Cost-Effective Email Forwarding Service Search

I'm on the lookout for a new email forwarding service that offers better pricing than Mailgun. Essential features that I require include:

- Email forwarding: Specifically, I need a solution that can accommodate a custom user base of around 500.

Ideal candidates for this project would have significant experience in assessing and implementing email forwarding services. They would have an in-depth understanding of such services' pricing models, be able to offer various alternatives, and demonstrate success in optimizing costs for clients in the past.