Aol mail not working in Mac Mail

I have had this problem several times and it's getting rather irritating. The SMTP servers are not responding. The following message keeps coming up:

Sending the message content to the server failed.

Select a different outgoing mail server from the list below or click Try Later to leave the message in your Outbox until it can be sent.

After changing ports and following the numerous suggestions experienced by countless others with the same problem time and time again I still have found no solid reason as to why this happens or how to simply resolve the issue.

If anyone with knowledge and experience can shed any light on this troublesome problem then please make yourselves known.

I have followed threads and made all the correct adjustments including deleting and creating a new email account. Is this an AOL issue or a Mac issue? The mail works fine on the ipad and iphone.

I have also tried using different wifi and cable connections with the macbook I have my account installed on. It's the latest software 10.8.4 and a macbook pro 13'. 2011 model.

Any help will be greatly appreciated.

Thanks.

Chris