What is the capacity of email-to-sms gateway?

I am doing a project for a club that would like to implement email-to-sms messaging to send text messages at medium-volume to our members. I was wondering what could I expect the volume of messages that I send through a email-to-text gateway to be before I would see issues with deliverability? For example, would I expect 5 message per minute before messages would not deliver to users.