When sending an instant message using Skype for Business, you may see the error message 'This message wasn't sent to ..' This can be caused for a variety of reasons.

Scenario 1

IM Issues with Mac Skype for Business Client. Pops below the message stating: 'This message wasn't sent to jdoe@contoso.com.' Interesting enough, the message IS sent to the user. Any follow-on messages to a user who is away from their computer will not be received by the recipient on a Mac. Only first message sent will be. Skype For BusinessThis message wasn't sent to william.nomates@blah.co.uk due to company policy. Working with an external company to do proof of concept testing for a new service. They use Skype for business, so I decided to add them as external contacts.

The first user sends an instant message to a second user. The first user sees a message like the screen shot below.

OR

Cause

This is due to a bug in the Microsoft Office Software released as an update sometime in October of 2016. The status that the user sees is showing that the second user is signed into Skype for Business Desktop client and a Polycom phone as well.

Resolution

Ensure both users update their version of Office or Skype for Business to a version that is at least 7766.XXXX or higher. To update Office see How to Manually Update Microsoft Office Products
Note: This resolution is not currently compatible with Mac computers. A compatible resolution is in development but does not have an estimated release date.

Scenario 2

The first user sends an instant message to a second user. The first user sees a message like the screen shot below

The second user sees a message on their mobile device like the screen shot below Remix os player system requirements.

Cause

This is due to the second user being logged into a Skype for Business Mobile Client and the second User ignores the message Parallels desktop for mac torrent.

Resolution

At this time, there is not a resolution to this since we are a hosted Skype for Business Solution, Microsoft doesn’t support server side conversation history. If they did support server side conversation history for a hosted solution, then User B who ignored the IM on their mobile device would get a missed conversation notification in their email and User A would not see an error message on their desktop Skype for Business client.

Work Around

Make certain that users are signed in to a single primary device. If signing in to mobile is necessary, sign out of desktop client.