I want to use sendgrid for sending password recovery emails and get the free version with the limit of 100 emails a day. I couldnt see what happens if that limit is reached. What if there is a user who during that day requests password recovery but it would be email number 101? would he just not be able to send it? Do I need to set up something myself on my backend? Would I be charged for the next plan?
After you pass the SendGrid emails limit, in your case (free version) - 101 email, you will get:
The 101 email will get rejected by the Sendgrid API.
SendGrid API will return a rate limit error response (status code 429). You can handle this error in your code, and you might consider sending the email through a different service or trying again later when the limit refreshes.