If you already own the domain, one way of staying free is to use Cloudflare email redirection. Cloudflare has a feature such that if you own xyz.com, they can redirect all mails coming to <address>@xyz.com to any other email you provide.
For sending, you can use any service such as Sendgrid or even plain SMTP/IMAP.
Redirections will still be included with domain names. It's actual mailboxes that were included and will cost ~60€ per year per mailbox, even for existing customers with domain names expiring years from now.
Are there any alternatives that provide domain+mail, that do not cost >1$ year per domain+mail account?
Or are there any mail services that allow multiple domains (not alias) for around 24$ year? Mail storage does not matter as long as it is of reasonable size >100 Mb.
I don't even use GandiMail and this sort of thing guarantees I'll be moving my (fortunately few) domains out of Gandi. Such absolute contempt for their customers. Once a company starts screwing over one class of users, it's only a matter of time before they come after something I do actually use.
For sending, you can use any service such as Sendgrid or even plain SMTP/IMAP.