This one took me a long time. Users were complaining they could not add calendars to their OWA because the option Add Calendar
is greyed out. I did a lot of research on this and could not find out why this happened. I found a handful of people with a similar issue online but alas without a solution. The best info I got was someone from Microsoft stating that there is no option in Exchange to disable this
. Through trial and error I found the pattern: it doesn't work for people who logon to their mailbox directly.
Usually you log on to OWA simply by surfing to https://$mailserver/owa
. This is an indirect link: it opens the mailbox based on your credentials. The other method, often used by mailadmins who need to log into a mailbox but also by some users, is a direct link https://$mailserver/owa/$emailaddress
In the latter case, you cannot add calendars. There is some kind of logic behind this, but god this was annoying.