Email is a pain and there are few add-on utilities that are likely to change that. Mail on my Mac has two utilities which help to reduce the pain. The first one is SpamSieve, a highly recommended utility for Mac users who get plenty of spam.
The second add-on is useful but in a far different way. It’s called SendLater and what it does is let you send email later. Instead of clicking the Send Message button, which sends the email immediately, you can click the Send This Email Later button, which lets you schedule exactly when to send the message.
When the scheduled time to send the message arrives, the message is sent.
Why would you need to send a message later, or on a schedule, rather than just click the Send button and send the message immediately?
Obviously, using SendLater is a good way to send more timely email messages for specific occasions (weddings, holidays, anniversaries, graduations, etc.), but I have an even better use.
When you respond to email at work your boss or coworkers know you’re always available. By setting a schedule, messages are sent when you want them to be sent. That means you can answer work messages later at night by not have them sent until you arrive at work. And it all happens automatically; no mucking around with draft messages.
I’ve been using SendLater for a year and it just works. Nothing fancy. Set the schedule and it sends the email messages accordingly. The only caveat, of course, is that your Mac and Mail need to be running at the appropriate time for the message to be sent.