Right, and beyond the value proposition of the email service, you are also serving your customers _by_ being profitable. Because this suggests that your service will be around in many years and hopefully won’t change in ways that users won’t appreciate (which is common with funded companies these days).
That's definitely the plan! One of the SaaS providers we use recently did an "upgrade" and now our team is struggling with everything being much slower and worse than it was before. It was a good instructive point to tell everyone in our all-hands Quarterly meeting yesterday that we are that SaaS for many others, and we have a responsibility to keep providing them a good service.
1) "how much profit have we managed to make?"
1a) (modulo exchange rates - it's more balanced now, but a few years ago almost all our expenses were in AUD and our income is all in USD)
2) "how many people can we hire with that profit?"
2a) (save a bit for a rainy day)
3) "hire the next roles off our roadmap while fitting within our means"