Earlier this month, we reported about Yahoo restricting how its email addresses are allowed to be used. Yesterday, AOL did the same thing. They published a new email security policy that directs many large email receivers to drop email from @aol.com addresses that does not originate from its own mail servers. This affects all email service providers, not just MailerMailer.
If you are using a From address in your newsletters that is at aol.com, the majority of your messages will bounce (we estimate anywhere from 40% to 90%) due to this new policy. The only solution is to use an email address from a different mail service.
Many in the industry feel this may be a trend among the free email providers. Even if you are using Gmail or Hotmail which are so far not affected by this, you should plan ahead for the time when they do implement similarly restrictive policies. The only future-proof course of action is to use your own private domain over which you have full administrative control to set your own policies on how it should be used. Google Apps provides an easy to use service to host your own email domain.