While Microsoft has been pretty quiet working on a reissue of the April CU, the community came up with a decent work around. I simply want to bring some visibility to it.
Stepping back, I see this as good news as the incoming email issue which obviously wouldn't be impacting everyone, since not everyone uses inbound email. As well, many will be using quotas which will exclude more.
Francois Souyri outlines a very well written explanation in his post "Found an issue [WITH FIX] with SP2010 April 2012 CU : incoming emails not going to SharePoint"
April CU Issue:
"Incoming emails to SharePoint are all configured properly and emails are being received in the server's SMTP Drop folder but they stay there and are not picked up by SharePoint."
Looking at the ULS logs you'll find this "E-mail cannot be delivered because site is over quota or locked for editing." That's the regression.
Essentially it's looking for a quota and it's blocked from inbound email unless there is a quota configured. That's the fix. Simply configure a simple quota and you're good.
If you're looking for a work around for the lazy approval with Nintex workflows you'll get more description from the same post above.
Kudos to Francois for pointing out this workaround and helping to share the solution with the community
Note: As of 5/29/12 as of this writing, the April CU has been taken down due to technical issues. It's nice to better understand the issue and find a decent workaround. Thanks again Francois.