`Go To Message ` link in email not working with Iframe integration and Logged out User.

Description:

Steps to reproduce:

1. Log in to rocketchat account after iframe integration done.
2. Send Direct message to one of your user account which is not online.
3. check the mail of the user account to who you did send an email.
4. Click on Go To Message Link button.

Expected behavior:

If Go to message link has been clicked from email message notification of direct message service.
of rocket chat. than this following cases should considered.

1. Clicked with already logged in in Rocket Chat.
   It should redirect to rocketchat hosted url for example http://rocket.chat:3000/direct/{username}
   (now this is working properly.)
2. Clicked with not already logged in in Rocket Chat.
   It should be redirect to Iframe Url instead of actual hosted Url. for example http://rocket.chat:80
   (this is not working)
   and same should happened if User is getting log out than too its should redirect to Iframe Url instead of site`s hosted url or root url.

Actual behavior:

in case no 2. link is not getting redirect to Iframe Url.
redirecting to site`s hosted url instead.

Server Setup Information:

• Version of Rocket.Chat Server: 0.73.2
• Operating System: Cent Os 7.
• Deployment Method: Download Source and Build as per guideline from official documentation.
• Number of Running Instances: 1
• DB Replicaset Oplog: Disabled
• NodeJS Version: v8.11.3
• MongoDB Version: 3.4.18

Additional context

Relevant logs:

No files or tests are named. Start by tracing how the email notification builds the “Go To Message” URL and how logged-out iframe users are redirected; compare logged-in, logged-out, and post-logout cases. Done means each case opens the iframe URL rather than the hosted root URL.