Hello and thank you for asking your question at JustAnswer
That issue is relative to AOL's POP (Or incoming mail servers). When you access your AOL account using Apple's Mac OS X Mail, the mail application pulls your emails from AOL's direct Incoming mail servers so if there is a delay in your mail, there may be an issue with either the service from AOL's servers directly or it may be from the Mac OS Mail application.
To work to remedy this, you can try one of two options or both:
1.) Use Safari (or Firefox if you prefer) and access your AOL via AOL's main webmail page.
-Check the times of the incoming mail in your mail box to see if they are up to date.
- Match the incoming mail in your AOL email account listed in your your open Mac OS X Mail application. If the time stamps for the recent mail are the same, then that is the issue right there and that means there is a latency from AOL's servers at this time.
2.) The other option is to remove the AOL mail from your Mac OS X Mail.
-Then before re-adding your AOL mail, run this repair process from within your Mac OS X desktop first:
-RUN DISK UTILITY FIRST-
Go to Finder Menu bar
• Click Go > Utilities > Disk Utility and open up Disk Utility app.
• Click on Macintosh HD volume (or on the name you have changed this volume to.)
• Select "Repair Disk Permissions"
*Let Disk Utility run this repair permissions until completion
Once Disk Utility is complete and there are no errors in red in the completion summary (if there are errors listed in red, re-run DU to see if those error will clear- if they don't reply back to this post right away and let me know what the exact error message is), quit Disk Utility.
• Now open Mail back up and re-add your AOL email account.
Once your AOL email has been re-added, check your most recent mail's time stamps to see if they are more current than before.
If they are still the same as the open webmail account, again, this is an issue with AOL's Incoming (POP) mail servers and you may have to alert them about this, so they can check your account from within.
If neither of these methods don't help, then my final recommendation is to click the link below and download AOL's own email client, AOL Desktop for Mac
Link: http://daol.aol.com/software/desktop-for-mac/ (Just copy and paste the link into your web browser and press Enter)
This a very good alternative actually- I have it and I use it exclusively for my AOL accounts only because I have not had too good success (personally and speaking only for myself) with the AOL to Mac OS X Mail relation.
Let me know if this helps.