IT-Pro: How to set the compose font in Outlook on the web and the New Outlook via PowerShell Script

Aligning the email font and the email signature font is essential for ensuring professionalism, consistency, and effective communication. A consistent font ensures your emails align with your brand image. Fonts like Arial, Calibri, or Helvetica exude professionalism, while unregulated fonts can appear unpolished or untrustworthy.

In the New Outlook, centrally setting the compose font via the 365 add-in or other direct methods is not currently supported because Microsoft 365 add-ins, including Xink, operate within specific constraints. These constraints limit their ability to change Outlook's default compose settings, such as font styles or sizes, as these are part of the core Outlook client configuration rather than managed through the add-in framework.

Change the compose font and font size Individually

Currently, I'm using the following font (Aptos) and font size (12).

First, you need to connect to Exchange Online (Type your Admin Credentials):

Connect-ExchangeOnline

Change the font and font size.

Set-MailboxMessageConfiguration -Identity username@domain.com -DefaultFontName Arial -DefaultFontSize 10

Restart the new Outlook client and verify your changes. Compose a new email and check your default font.
To change company-wide, you can run the script below.

Get-Mailbox -ResultSize Unlimited | Set-Mailbox -DefaultFontName "Arial" -DefaultFontSize "10"

You can also try the script below. Make sure to modify the command to your required font and font size.

# Query all the mailboxes
$Mailboxes = Get-Mailbox -ResultSize Unlimited
 
# Loop through each mailbox
foreach ($mailbox in $mailboxes) {
    # Apply desired settings
    Set-MailboxMessageConfiguration -Identity $mailbox.Identity -DefaultFontName Arial -DefaultFontSize 10
}