Hi @Yohann Demeulemeester ,
Based on your post regarding with Outlook pop out "Retrieving Templates from Server" when write a new message. The Outlook Team is investigating this issue for a fix. The current estimate is for the fix to be implemented in March 2023. When we get the fix build and release date, we will update this topic with that information.
To work around the issue, you can select Cancel on the prompt and proceed to choose the from account to send with.
However, if you urgently need to avoid the prompt, you can try reverting to the build before the issue started. In initial reports of this issue the problem appeared to start in Version 2206.
For Extra reference see: Outlook prompts “Retrieving templates from server” after selecting the From field drop down - Microsoft Support
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