Hello, this is unfortunately a known issue to us, it can occur when the Outlook.com servers are not able to process the volume of requests being sent to it, the issue should automatically be resolved by the application by retrying the access and re-uploading the item you’re trying to synchronise or that the application is trying to synchronise.
This issue occurs in your calendar, so the problem is with a calendar server, but unfortunately on this type of account it is not possible to synchronise the calendar using a different protocol, however you can setup your mail account as an IMAP/SMTP server which would allow you to synchronise your email items properly. It would however disable the ability to synchronise your calendar and contacts items with the server.
Thank you for the suggestion, I agree, we’re currently working on an upcoming release which will feature a re-designed UI, one of the first mockups have included this option, so I believe it should be included in the final as well.
So, can I ignore the notice of error 503?
Will it cause issues down the road?
Will it be gone with the upgrade to 7 when that comes?
Will I be able to upgrade since I have a free account?
I agree. These occur very often for me too and it would be great to have an option to always ignore these error; especially since the client will retry to sync.