This site is the business equivalent of my SimpleSamples.info.
This site is hosted by 1and1. Most of my web sites are hosted elsewhere but all my email is hosted by 1and1.
Some Windows hosts, such as Microsoft Azure, do not include email in their hosting plans. There are many providers of "hosted email" solutions (including Microsoft Exchange Online) at reasonable prices but with that all your email accounts are combined into one mailbox. If you only need email then you can get an economical Web Hosting package from 1and1 even if you only use it for email. For example they currently have a special for their Unlimited plan for $1 a month for 12 months, then $8 a month after 12 months. With the plan you can have an unlimited number of email accounts, each with separate mailboxes and for multiple domains registered wherever you have them registered. I am not sure, but if you truly only need email and no hosting then perhaps their Basic Mail is all you need. It is $2 a month for 20 mailboxes (be sure to use the drop-down to get 20 mailboxes).
When evaluating 1and1 plans, be sure to click on the "Show fineprint" link at the bottom of relevant pages to see details of the plans.
I have had a free email account with GMX for a few years. GMX is provided by 1and1. Based on that, I know 1and1 is reliable. That is what lead me to them.