calendar synchronisation error

I am constantly getting Error messages "The remote server returned an error (503) Server Unavailable) This has been happening regularly since I installed eM Client (latest version) a few days ago. My server is Hotmail/Outlook.  I need to make the decision whether to purchase but not if this keeps happening.

Hello Graham, can you please make a screenshot of the error? We’ve came across this issue with couple of our users, but this error is mostly thrown when your mail server is unable to handle the number of requests he’s processing. The issue was also held within the synchronization of the calendar rather than your e-mail.

eM Client is using the AirSync protocol that’s used for synchronizing your whole account, due to use of this protocol, we’re unable to distinguish between settings for your mail and calendar service, so if one works, all should. Based on this premise we’re quite positive this is mostly a server issue.

But just to make sure, can you please go to Tools > Settings > Advanced and enable AirSync logging for the problematic account? Save the settings and replicate the issue, once the error reoccurs, please restart eM Client and go back to the advanced settings window to submit the logs.

Please submit the logging data to my work mail, with a reference link to this forum topic.