Unable to send invitation emails for my team

Hello, I just installed Ghost using the Marketplace of DigitalOcean. I connected my domain. But when I want to add a new staff in Ghost, the website give me an error: Request was rejected due to server error

I changed nothing in the code, I try to reinstall Ghost but it is not working.

Can you help me please ?

Sounds like you might need to configure your mailserver. That’s a transactional email that’s failing. See Configuration - Adapt your publication to suit your needs for more on the differences between email types.

I don’t know what kind of mailserver you have on your droplet, but if you google it and ghost email, you should get some hits.