I am new to cloudways how to make domain based email for wordpress website in cloudways
For domain-based emails and wants to receive emails, then you need a service like Rackspace. 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.
If you need transactional emails only (newsletter, reminders, signups etc) then Mailgun offer a free package which is very useful.