Some external mail providers such as Google and Microsoft operate at the sort of scale where it can be assumed they know what they are doing, and as such their services are probably going to be of good quality. Equally, some mail services from smaller web hosts will not always be up to scratch, which may be a reason to try connecting to an external service.

Note that many free web hosts do not permit external SMTP connections, in an effort to make it harder for anonymous customers to send spam. Other that 000webhost, all the others I tried blocked the mail ports at their firewall. However, if you are on a paid account, you will normally be fine.

If you already use a provider below for your personal or business email, I recommend you get a separate one for your Missive form app. That way, if your password becomes compromised, the amount of security damage will be minimal.

GMail

This works very well. The settings are as follows:

Encryption TLS
Host smtp.gmail.com
Username your.account@gmail.com
Password your.gmail.password

You have to make one additional setting change in GMail, which is thus:

Even though it sounds slightly alarming, I take the view that this feature is perfectly safe to use. Google does offer other authentication systems which do not need this switch (particularly OAuth2) - seeing if that can be integrated is on the roadmap.

Other providers

I’ll test some more of these in the future. I imagine free accounts from any of the following would be just fine: