In TeamCity's administration settings you can specify the YouTrack project IDs in a comma separated list.
But what if your project IDs in YouTrack have spaces in them? For example when you branch your project after releasing version 1.5 one could have a new project ID: Project 1.5
Project 1.5-1 would then be the first issue ID.
Specifying this new project ID in TeamCity won't work: Project Project 1.5. Should it become: Project "Project 1.5"? Or maybe it's better to just make it a comma-separated list of project IDs: Project,Project 1.5