@scamando Excellent answer!
Hi @Remco Except for Vultr and GCE, all default emails are sent without setting up any SMTP on server OR application. It is because the port 25 is blocked by the two providers.
If you set-up SMTP on a server. All the applications hosted on that server will use those SMTP credentials. To use separate credentials on different application installs, you need to set up SMTP on applications individually.
The above is for transactional emails.
And, if you want to receive emails. Then, you need to get an account for email hosting. Rackspace is considered as one of the best email hosting provider. We had a deal with Rackspace, you will get an email account for only $1/email/month instead of $2/email/month (their official pricing).
However, if you want to get a free email hosting. Then, Zoho mail can be the best option.