I used Face2Face for a long time and loved it. MailButler incorporates the features offered by Face2Face, works great and has a bunch of other nice features.
Even when you have a subscription, they plaster your mail app with ads for their business plans. Thet's ridiculous. They promised new features but magically these are only added to the business plan that's 3 times the price. That's not how you value your customers.