Hello everyone, I've first tried to ask this question to the general Microsoft community (answers.microsoft.com/en-us/outlook_com/forum/ocalendar-oimportcal/two-way-calendar-sync-between-outlookcom-and/e1d89b7d-816c-4399-bd7c-6c507356d69a) but got asked to post it to Technet. 

I've been trying to add a two-way sync for my outlook.com (365 subscription) to Thunderbird's now integrated Lightning plugin. For the actual connection I use the following plugin: https://github.com/Ericsson/exchangecalendar/releases

I cannot get this setup to work, there are some posts and tutorials that suggest using various server URLs such as:

hxxps://pod51011.outlook.com/ews/exchange.asmx

hxxps://outlook.office365.com/ews/exchange.asmx

But none of these work, they all return a 500 internal error message, meaning these URLs are probably not used (anymore) for these requests. Other tutorials and messages that describe successful setups use private domains with their own exchange servers.

So, my question is: What is the URL I can use to sync my calendar with Thunderbird?

Hi,

This forum is for questions, feedback, or anything else related to Microsoft Office client. If you are encountering problems while using Outlook as your mail client, we will be able and happen to provide our suggestions. Since your question is more related to Outlook.com and Thunderbird, and we are not familiar with these two products, I'd recommend you contact the Thunderbird support or post a new question to the Outlook.com forum to get further assistance:

http://answers.microsoft.com/en-us/outlook_com/forum/ocalendar?tab=Threads

The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction with us. Thank you for your understanding.

Steve Fan
TechNet Community Support

I've already tried to find a solution on the Thunderbird side of things, but like I said, all people that were successful used it on the exchange server of their company or university while I want to use it on the publicly available Office 365 servers.

As to your link, I am not sure what you want me to do with it, this very thread appears on the first page, together with threads that are unrelated or still run into the same problem.