For a number of reasons, I’ve kept my AOL email account, but have naturally incorporated it into a single mailbox using fetchmail and AOL’s imap interface. I noticed that fetchmail started doing this all of a sudden:
fetchmail[90687]: Server certificate verification error: unable to get local issuer certificate
fetchmail[90687]: Server certificate verification error: certificate not trusted
After some investigation, it appears that fetchmail is suddenly having trouble negotiating a TLS connection via IMAP. Beats me why — it either didn’t make the attempt before or something has gone funny on the AOL side — but aside from being vaguely annoying, it turns out that the mail still gets through, and these errors effectively mean nothing whatsoever.
This is an fault on AOL’s side more than fetchmail. The root ssl certificate for AOL mail is setup based for thier webmail client and since fetchmail does not issue client side certificates by default. The error is displayed.