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Email signature logo showing as attachment

Last updated November 8, 2026. Written by Email Signature Gen.

A logo shows up as an attachment when the picture travels inside the message instead of being linked from the web: it was embedded from a file, or the message went as plain text, which can't show pictures in the body. The fix is a logo linked from a public HTTPS address, in a message sent as HTML.

The usual causes

  1. 1. The message or reply is in plain text

    Microsoft says plain text doesn't support showing pictures inside the message, and that a message you send as HTML can be converted to plain text if the reader's mail app is set to convert messages.

    Source: Microsoft: Change the message format to HTML, Rich Text Format, or plain text in Outlook

  2. 2. The logo is embedded from a file

    A logo inserted from a file on your computer is a file inside each message. Whether the reader's mail app shows it in place or with the attachments is up to that app.

In Outlook

  1. 1.Send in HTML. New Outlook: Settings > Mail > Compose and reply, set Message format to HTML, then Save. Classic Outlook: File > Options > Mail, and under Compose messages choose HTML, then OK.
  2. 2.Remake the signature with the logo linked from a public HTTPS address, not inserted from a file.
  3. 3.Send yourself a test to a different mail app.

Source: Microsoft: Change the message format to HTML, Rich Text Format, or plain text in Outlook

In Gmail

  1. 1.Open Settings > See all settings, and find the Signature section.
  2. 2.Turn off plain text mode if “Plain Text” shows above the box.
  3. 3.Replace the logo with one from a public web address, then click “Save Changes”.

Source: Google: Troubleshoot issues with Gmail signatures

How Email Signature Gen handles this

Signatures from Email Signature Gen link the logo, photo and banner from your host. The HTML we copy never attaches them, so there's no file in the message to turn into an attachment.

A message sent as plain text, or converted to plain text by the reader's mail app, still can't show pictures. That's outside the signature.

Questions

Why does it happen only on replies?

A reply can go out in a different format from a new message. Microsoft says plain text can't show pictures in the message, so check that the reply is in HTML before you send it.

Can I stop it for every reader?

Linking the logo means there's no file in the message to attach. The reader's own settings still decide whether pictures load.

Does Apple Mail do this?

This guide doesn't cover Apple Mail, so we don't make a claim about it.