Mailbutler has been an effective tool to confirm that my emails have been opened by my clients instead of wondering if they went unopened or into their junk mail. Also, I love to schedule my emails and optimize the best time. I can also add Mailbutler to my Chrome browser with an extension to use with Gmail.

I love the send later option and that I can create tasks out of emails that are created directly in trello. It works seamlessly.

I really like the ability to schedule e-mails to be sent at various times during the day. Particularly useful is the tracking of when the e-mail is opened and when any links in the e-mail are clicked on. The ability to add a follow-up task is particularly useful as it prevents losing track of important conversations.