Is that an iOS 7 thing? Because I haven't seen it in themes for iOS 6.
Even so, I wouldn't use a sound theme. I use all of the sounds from my old WinMo phone, plus for email I've copied over the mail sounds from Entourage 2004, 2008 and Outlook 2011. I use those for my various email accounts.
Even my alarm sound is the same as the one I used to use on my HTC Touch Pro.