TL;DR: Not much.
Aol’s inbound mail infrastructure has been pretty wobbly for a while now, at least from the point of view of large senders. Though things seem to have improved since around April of last year, for a while intermittent outtages of their inbound MTAs had becoming something of a recurring challenge, and the punchline for a few jokes traded on Twitter.
Aol was the first to do a lot of cool things in the email space. They were the first to offer feedback loops, whitelisting services, and among the first to provide senders an idea of what their sending reputation might be. But it’s hard to stay in the front of the pack, especially when you’re facing challengers like Yahoo, Google, and Microsoft.
After years of losing eyeballs, Project Phoenix was announced in 2010. It was an ambitious idea that sought to create a slick, unified messaging platform that included mail, SMS, social media, and other channels. It earned kudos from the user community, but it never quite gained the traction it needed to re-position the company in the messaging space. Development on Phoenix was halted after less than a year.
Verizon isn’t shelling out US$4.4-billion for Aol’s eroding email user base, as many others have pointed out. That means I wouldn’t expect Verizon to prioritize any fixes for what may still be broken with Aol mail.