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Apple Mail signature logo on Mac: add it, fix attachments

Add a logo to an Apple Mail signature on a Mac by dragging the image into Mail settings. Fix logos that arrive as attachments or show as broken boxes.
The Sendoff team4 min read

On a Mac, open Mail > Settings > Signatures, pick the account and paste your signature. If the logo is missing, drag the image file into the right-hand pane under the text. If it arrives as a file or not at all, make the message rich text with Format > Make Rich Text, because plain text cannot hold an image.

Can you add a logo to an Apple Mail signature?

Yes, on a Mac. Apple's Mail guide says you can "enter the text of your signature, change formatting, add images, and preview how your signature looks." The iPhone is different. Its signature box takes text only, so a logo added there may not appear. For the phone, read the iPhone Mail logo guide.

How do you add a logo to a Mac Mail signature?

  1. Open Mail and choose Mail > Settings, then click Signatures. Older macOS versions may label this Mail > Preferences.
  2. In the left column, click the account the signature belongs to.
  3. In the middle column, select your signature, or click + and name a new one.
  4. Untick Always match my default message font before you paste. The font guide explains why this matters.
  5. Paste the signature into the right-hand column. If you use Sendoff, press Copy signature in Safari or Chrome first.
  6. Check the logo in the right-hand column. If you built the signature by hand and the logo did not paste, drag the logo file from Finder into the column, under the text, where you want it. Apple's guide describes dragging an image into this column.
  7. In the Choose Signature menu, set this signature as the account's default.
  8. Close settings, start a new message and check the compose window. Then send a real test to a Gmail address and an Outlook address, and check the copy that arrives.

Why does the logo arrive as an attachment?

A plain-text message cannot show a picture inline. Apple's guide on plain and rich text says plain text leaves out formatting, tables and images. Open the message and look in the Format menu. If it offers Make Rich Text, the message is plain text. Choose it, insert the logo again and send a test.

Apple Community has threads with titles such as "Email signature appears as an attachment" (see Sources). We did not confirm their answers. Apple's documentation does not say when Mail sends an inline image as an attachment, so test any fix on a real message.

Why can't recipients see the logo?

Many mail apps hold back images from a web address until the recipient allows them. Apple's page for this says the message shows "Unable to load remote content privately" at the top, and the recipient taps Load Content to see it. Apple's page talks about remote content in general and does not mention signatures, but a hosted logo is remote content.

Design the signature so it still works with the logo hidden. Keep the name, role and phone number as live text, and give the logo alt text so the recipient sees a description.

Why does the logo look broken or show as question marks?

Some users see a broken logo while composing. A reply in the same thread says the sent copy then shows the remote-content warning instead, so open the sent message and check what it displays. An Apple Community thread from October 2021, written after Monterey and iOS 15, describes hosted images in an HTML signature that showed as question marks in Mail, although the same HTML worked in browsers and other apps. The top answer, from January 2022, says to change a Dropbox share link from dl=0 to raw=1. That is one user's result, not Apple guidance. Host the image on an address that returns the image file itself, not a preview page.

Troubleshooting

  • The logo is missing in the settings pane but shows in messages. Judge the sent message, not the settings pane. Send a test to a second address.
  • The logo is a broken box for recipients. Open the image's link in a browser. If it opens a preview page instead of the picture, change the link.
  • The logo never shows in new messages. Check that the signature is the default for this account under Choose Signature. A signature set on another account will not appear here.
  • Only text reaches your iPhone. That is expected. The phone signature box keeps text only.

How Sendoff handles this

Sendoff stores an uploaded logo as a public PNG at an HTTPS address, so you do not need a separate image host. The logo is 120 pixels wide by default, and you can set it from 40 to 240 pixels. Copy the signature from the free email signature generator, then follow the steps above. The full setup is on the Apple Mail install guide.

Sources

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