Forum Discussion
Can't access shared mailbox?
jab9417 Hi Jab, I'm having the exact same problem that you're describing here. A linked account in a subsidiary domain isn't able to access certain shared mailboxes on Outlook versions newer than 2013. They're able to use OWA and Outlook 2013 just fine, but cannot open the box on 2016 or O365 versions of outlook.
Have you found any solution to this issue yet?
JJones1216 Sorry for the late reply. Here's what I found in my case: In my scenario the shared mailboxes on the remote domain (lets call it child.com) had been assigned an email address from my domain (parent.com). This @parent.com address was set as the reply address for the shared mailbox and all the usual server and SPF stuff was done so they could send using our domain name.
As we migrated users from child.com over to parent.com, the former child.com users that needed access to these mailboxes couldn't access them anymore. I knew it wasn't an access issue, because their old child.com accounts worked fine while on a child.com computer, it just didn't work from a parent.com computer. In my brain, this really only left some sort of name resolution issue. As a test, I removed the shared mailbox from outlook, switched the shared mailbox's reply address back to the @child.com address, re-added it Outlook, and VIOLA! it worked. So, I reset my email address policy on child.com to set the child.com address as the reply, resolving the resolution issue and giving my a feasible workaround while I got the users migrated, and then I just double timed my migration of the shared mailboxes once that was complete.
Ultimately, I think the issue has to do with how outlook, autodiscover, and DNS work together. When Outlook was trying to open these @child.com domain shared mailboxes that were using @parent.com addresses it either couldn't figure out where to go to access the mailbox, or couldn't figure it out quick enough and just timed out. There is probably a better, more elegant fix for this, but this workaround worked for me.
jab9417 Thanks! In my case it ended up being that our (to use your terminology here) child.com domain had setup grandchild.com and not ever actually created autodiscover records for it (this was the only mailbox ever used on that domain)... for some reason Outlook 2010 was still able to resolve these correctly on child.com domain-joined systems, but outlook 2016/365 was not. Outlook 2016 only worked on parent.com domain-joined systems. The fix for us ended up being to just add a grandchild.com autodiscover dns forward pointing to parent.com in our child.com domain controllers.