I've been very happy with agentmail.to for a while with great success. You get 3K free emails per month with 3 inboxes. Paid tier starts at $0.20 per 1000 email

I've been very happy with agentmail.to for a while with great success. You get 3K free emails per month with 3 inboxes. Paid tier starts at $0.20 per 1000 emails. Disclaimer: I don't work for agentmail.