Outlook sends messages on startup but outbox is empty because of stuck read receipt confirmations, Messages stuck in outbox

 I run into two issue with Outlook 16:

1. Outlook says sending x of y messages on startup, but outbox is empty
2. Messages are stuck in outbox

How-I-fixed-it:

I found out, that the lock was caused by read confirmations stuck in the send queue, which did not occur in the outbox.

First of all, I disabled the read confimation sending in the Outlook options (E-Mail -> Read Receipts)

The solution then was to abort the submit of the stucked read confirmations using the Tool MFCMAPI as described here:

Delete a stuck Read Receipt - HowTo-Outlook

Outlook Office365 Work Account Error 0xCAA70007

Outlook 365 0xCAA70007 error message connecting to onmicrosoft Office365 account: You'll need the internet for this 0xCAA70007

Hi,

I'm facing an issue with accessing my onmicrosoft Office365 account with outlook. Whenever I open outlook in windows it shows the prompt "You''ll need the internet for this". The message says we couldn't connect to one of the services we need you sign you in. Please check your connection and try again.

The error code is - 0xCAA70007

The outlook works fine in the browser and internet connection is working.

I tried repairing office and also removed outlook credentials.  I have also uninstalled office and now the client will not even load.  

How-I-fixed-it:

I found the solution to my problem in Microsofts answers:

https://answers.microsoft.com/en-us/msoffice/forum/msoffice_outlook-mso_win10-mso_o365b/youll-need-the-internet-for-this-0xcaa70007/a1d80f08-27b5-406c-8e07-a8e6bb8c2d1b

This is what I did:

• Shut down all Office Apps
• In Explorer, navigate to  C:\Users\%Username%\AppData\Local\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\AC\Microsoft\Crypto\TokenBindingKeys\Keys
• Delete the Keys in the folder
• Relaunch Outlook - Keys are re-created automatically.