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How to change the default font and signature font in Outlook

Change the default font for new messages and replies in Outlook, then set the signature font in its editor. Steps for classic Outlook, new Outlook and the web.
The Sendoff team4 min read

Outlook keeps the default font for new messages and replies in mail settings. The signature has its own font, set inside the signature editor. Change the message default first, then format the signature, then send a test email to check both.

Does the signature font follow the default message font?

Microsoft's help lists them in different places: the message font under mail options, and the signature font inside the signature editor. Set each one on its own, then check the result in a test email.

How do I change the default font in classic Outlook?

  1. Select File > Options > Mail.
  2. Under Compose messages, select Stationery and Fonts.
  3. On the Personal Stationery tab, under New mail messages, select Font. For replies and forwards, use Replying or forwarding messages instead.
  4. In the Font box, choose the font, style, size, and color. The preview updates as you change them.
  5. Select OK three times.

Microsoft says you set the font for new messages and for replies and forwards separately. To go back to Outlook's original default, use +Body, Regular, size 11, and Automatic color.

How do I change the default font in new Outlook?

  1. On the View tab, select View settings.
  2. Select Mail, then Compose.
  3. Under Message format, choose the font, size, and style.
  4. Select Save.

In Outlook on the web, go to Settings > Mail > Compose. Set Compose messages in to HTML format first. Microsoft says you can change fonts if you use HTML format. Then choose the font and size and select Save.

How do I change the font inside the signature?

In classic Outlook:

  1. Open a new email message.
  2. On the Message menu, select Signature > Signatures.
  3. Under Select signature to edit, choose your signature, or choose New and name it.
  4. Under Edit signature, select the text and change the font, font color, and size.
  5. Under Choose default signature, pick a signature for New messages and one for Replies/forwards, or leave them as (none). Select OK.

In new Outlook:

  1. Select Settings, then Accounts > Signatures.
  2. Select Edit signature next to the signature.
  3. Select the text, set the font, color, and styles, then select Save.

The checkboxes below the editor decide whether the signature goes into new messages and into replies and forwards.

Why does my signature show a different font when I send?

Microsoft's pages do not cover this case. The steps below come from Microsoft Q&A threads.

In a thread opened on 22 June 2026, a user set the signature to Aptos, but new messages showed a font that looked like Times New Roman. Four other users marked it as the same question. A Mac user in the same thread reported the same change on 7 July 2026: the signature preview showed Aptos, but the draft did not. Deleting the signature and recreating it fixed it on the second attempt.

Microsoft's default-font page says the default body font is Calibri. Some users say recent builds show Aptos instead. I could not confirm that change in Microsoft's documentation, so check the font in your own build before you change anything else.

Why does the font reset after I restart Outlook?

In a Microsoft Q&A question from May 2024, a user on Outlook 2021 LTSC said the new-mail font went back to +Body after each restart. Repairing and updating Office had not helped. A Microsoft moderator suggested three steps: check add-ins under File > Options > Add-Ins, create a new Outlook profile, and reinstall Office. The user replied that the reset affected new messages only, not replies.

Work through those steps in order. Change the font and restart after each one, so you know which step helped.

Can an admin set the default font for everyone?

Microsoft documents the Exchange Online cmdlet Set-MailboxMessageConfiguration with the -DefaultFontName parameter. Its stated scope is the font for new messages in Outlook on the web. The default is Calibri. It does not change the Outlook desktop apps.

A February 2024 Microsoft Q&A thread with 11 answers suggests this command for all mailboxes:

Get-Mailbox -ResultSize unlimited | Set-MailboxMessageConfiguration -DefaultFontName "Arial"

A reply in that thread says it only covers mailboxes that already exist, so new users need the same command in an onboarding script. Use your own font name, and test on one mailbox first.

How Sendoff handles this

  • The Font setting in the signature editor writes the font stack on each text element as inline CSS. The font is in the HTML you copy, not only in the editor.
  • The font list includes Arial, Helvetica, Verdana, Tahoma, Trebuchet MS, Georgia, Times New Roman, Garamond, and Courier New, plus web fonts such as Lato and Roboto. Calibri and Aptos are not on the list. In clients that skip web fonts, the next font in the stack shows.
  • Sendoff cannot stop Outlook from restyling a pasted signature. Send a test to a second account and check the font in the copy that arrives.

Build the signature in the free email signature generator, then follow the Outlook install guide.

Sources

Microsoft Support:

Microsoft Q&A (community answers, not official guidance):

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