Requires a programmer to set up, but works great

This has been a very largely set-it-and-forget-it plugin for the past 3 years for us. We use it to send DMARC-enabled emails from our WordPress contact form. Mailgun has been a great web service and costs pennies or a few dollars a month. We recently started using MailJet as well for sending bulk mailings. If you’re sending email in 2020, you probably want to use DMARC to ensure your mail is delivered and that your return address can’t be spoofed. If you’re using DMARC, Mailgun is fantastic.

It’s great to use the same solution for our WordPress sites as for our application products! Also to be able to create subdomains for each so that mail from each source is certified independently of the other sources.