Best EMail Client

I use airmail. It may not be free, but it's much better and very customizable compared to OS X Mail

For those using things other than Outlook or Apple's Mail, how are the printing features? Apple's Mail is sorely lacking when it comes to controlling how your emails will look when they print out... especially in Mavericks. You actually had some decent options in Mountain Lion, but they are gone now. I know I must sound like a caveman since I'm talking about printing emails, but this is for my tech support clients (who are of a certain vintage) who print a lot of emails.