When comparing Polymail vs Postbox, the Slant community recommends Postbox for most people. In the question“What is the best desktop Email client for Windows 10?” Postbox is ranked 7th while Polymail is ranked 14th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro One-click unsubscribe
Pro Free tracking option
Using a tracking pixel that will allow the user to know if an email has been opened.
Pro Scheduled follow-ups
Pro Responsive dev team
Pro Viewed as the eventual successor to Mailbox
Pro Clear interface
Pro Forgotten attachment reminders by default
Reminding the user that they forgot to attach the file if they mentioned one in the body of the email is one of the most useful features of any email client and so many don't include this. Postbox is pre-configured to look for certain keywords (attached, CV, spreadsheet, pdf etc) and you can specify your own keywords in addition.
Pro Blocks tracking gifs
Has the ability to block tracking gifs commonly used for read receipts.
Pro One Inbox for all accounts
All messages in one place. But you can select to show only messages from each account either.
Pro Quick Bar for macros
Quick bar allows you to add a variety of content to your message. It will let you reuse URLS in your Sent folder, and autocompletes against canned responses, signatures, and topics.
Cons
Con Expensive
Con Buggy
Con Still in invite-only beta
Con No support forum
Support for paid product has no online forums.