The best thing about this service was that it's free to use for up until 15GB per month, which I used quite often throughout my time at Mailbox! It also has an API so you can integrate with other services (like Zapier). Nothing really - everything works well enough but not anything in particular stands out as amazing or terrible either way :D If your looking into using email management software like mailchimp/zapiers etc then go ahead because they're very easy integrations too if needed :) We were solving our internal communication problems by being able to easily send emails from one place instead having them spread across multiple apps such Slack & GSuite Inboxes + Gmail / Outlook Email addresses.