You have to retain your domain, I assume you know this, that cost can't be avoided.
Otherwise you can sign up for mailgun:
https://help.mailgun.com/hc/en-us/a...-Differences-Between-the-Free-and-Flex-Plans-
Get the flex plan, it needs a credit card but you'll only be billed if you exceed that limits which should be very hard if indeed you don't have much email.
Add the DNS records:
https://documentation.mailgun.com/en/latest/quickstart-sending.html#add-sending-tracking-dns-records
Add a receiving route, with for example the following format:
match_recipient(".*@mydomain.com")
forward("
[email protected]")
You can be more specific on your match recipient or be as generic as I show.
If you leave it generic any email going to @mydomain.com will be forwarded to your gmail account.
This takes care of receiving the email.
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To fix the sending part you'll need to create a specific email address in gmail, you do this by adding a sending account, create an SMTP credential in mailgun, add it to gmail, let gmail send you the verification email and once verified you can select that email name as your sending address.
Now your only cost will be if you want to send/receive > 1000 emails a month per domain (mailgun account per domain)
And renewing your domain.
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I believe CloudFlare offers something similar btw, but I haven't explored it and it also doesn't cost anything, the catch is, CloudFlare must be your registrar.
That isn't as bad as you think you might think, CloudFlare has 0 fees for registration, they charge you what they pay.
However to move a domain from one registrar to another, you have to pay for a renewal.
Even if your domain, has say 1 year left on it, you'd pay the normal 1 year register fee to move it, but it would add an additional year to your domain (ie. it is not a transfer fee, it is a renewal as it gets added to your current time on your domain).
I've stuck with mailgun (for my email I mean) because they allow sub-domains at no cost. (ie.
[email protected]) whereas CloudFlared charges $10 p/m I believe for sub-domain level features.
If you don't use sub-domains, I'd highly consider CloudFlare.
I've already moved to CloudFlare as my registrar, they offer too many great features at no cost to not do that.