A few comments about Freemail Providers (gmail, hotmail, yahoo, etc);

Nothing is free.

If you are using an e-mail provider that you don't pay for, you are the product. As your searching habits and e-mail content are analyzed, inspected, and categorized, your habits become the traded commodity. This tracking process is designed to eventually manipulate your sensibilities and maximize profit at your expense. Eventually, you will pay for the "free" product.

The most immediate cost to your transaction is that you end up being the target of product sales and further promoting predatory product normalization. Wasting your time with annoying advertisements is the start, but longer term ramifications are becoming more apparent.

Freemail providers categorize large quantities of tracking information on each user and share these with advertisers. With time, compute availability becomes more cost effective and a more surgical targeting process can be used to alter the visitors emotional stability in real time. What was once just more accurate advertisement targeting quickly becomes more sinister as companies have found ways to use this sensibility manipulation to alter the course of elections, and promote inaccurate information and propaganda for power gains. As processes become even more accurate, this information will be used to blackmail and scam users in real time.

Freemail providers are less secure.

Aside from compromising your personal privacy, which is typically used to manipulate your impulses, sell you trinkets you don't need, and alter the course of elections, there is a more immediate value to not using freemail providers in the form of identity safety.

It's pretty simple to signup for a free e-mail account that looks similar to a popular figure or name. This is considerably more difficult to do this at a domain that you own and e-mails that you host. This is particularly important for business employees, which may be known only briefly by name via phone or and in-person meeting. Identity theft or fraud in their name becomes easier when a freemail provider is used. The barrier to entry is minimal for scammers compared to the alternatives.

You could make an argument that someone could purchase a similar domain name to attempt identity theft. Although this is true, this quickly becomes easier to track down and report to authorities than an anonymous e-mail provided by a freemail service. Setting up a new e-mail domain requires domain registration, SPF, DKIM, DNS management, and a few skilled parties. This is still possible with fraudsters, but generally less common.

(BTW, e-mail domain setup is pretty trivial with KYNGIN, but if you are interested in setting up a commercial e-mail domain to aid in scamming a target party, you've failed our ToS compliance and we aren't the service provider for you).

It's a regular occurrence here to see e-mail from freemail providers attempting to look like someone they are not, and this fraud has caused a number of our customers financial stress and loss of brand strength.

Find a trustworthy e-mail provider that has a non-nonsense Terms of Service and Privacy Policy, respects your privacy as a human, and is backed by decades of putting customer security and privacy first. Quite objectively, this is not any Freemail provider we are aware of.

Finally, when a problem comes about with a freemail provider, such as lost password, or data breach, there is usually very few people to speak with and get it sorted out. A number of our customers have lost access to e-mail accounts that have been hacked or compromised on freemail domains. This is less of a problem now that most support 2FA with recovery options, but the problem is still worth considering.

When trouble does happen, can it be resolved quickly? Or will you be in a situation where years of e-mail history are no longer in your control with no way to reach anyone @freemailprovider?

Freemail providers reduce brand strength.

Freemail providers are free, and because of this they are found to be used by many small businesses and independent shops. Conducting business using freemail domains may be a small cost savings initially, but it's likely costing you more than you realize with lost opportunities and a reduced confidence by your customers.

Convenience note...

We understand there are conveniences with using freemail providers. Typically in the form of getting more "free stuff" (calendar applications, team management, etc). But, most of these free things are pretty low quality products designed only to keep you locked into the application stack. Search a bit and you'll find that much better options exist. Many of these options are not only free, but aren't designed to lock your data into a specific vendor.