Using New Outlook on Windows for professional communication and productivity
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At this time, New Outlook does not support setting a default line spacing (for example, 1.5 lines) for all new emails. You can manually adjust the line spacing while composing an individual message, but there is currently no option to make this the default behavior.
I agree that this would be a convenient feature for users who prefer consistent formatting in their emails.
There is an existing feedback item for this request. If you'd like to support it, please consider upvoting and commenting on the feedback here: Edit styles / save line spacing · Community
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