Multiple Images or Signatures in Sent Mail

When sending campaigns with MailMerge365, you may notice the signature logo or other embedded images appear multiple times in the final email (usually as attachments) - sometimes even though the preview displays the message correctly. This behavior can be confusing, but it is usually not a MailMerge365 malfunction. Instead, it results from how Outlook handles signatures and inline images within drafts.

Common Causes

• Using the Outlook auto-signature feature in combination with manual signature edits
• Reusing older drafts that contain previously duplicated signature blocks
• Copying signatures from older messages
• Outlook automatically re-inserting signatures after saving a draft
• Multiple embedded cid: images stored in the draft’s HTML

Why Multiple Images Appear

1. Outlook’s Signature Editor Embeds Images Repeatedly

Outlook does not reference signature images from a single source. Each time a signature is inserted, edited, or carried over from a previous template, Outlook embeds the image directly into the email as an inline attachment. Over time, drafts may accumulate multiple inline images, even if they appear only once visually.

2. MailMerge365 Sends the HTML Exactly as Outlook Provides It

MailMerge365 extracts the full HTML of the Outlook draft, including all embedded images - even those that are not visible in the editor. If the draft contains multiple hidden inline images, all of them will be included in each merged email.

3. Previews Do Not Show Hidden Inline Attachments

MailMerge365's preview renders the email content but does not display duplicate inline attachments that may exist in the underlying HTML. As a result, users may only notice the issue after the campaign is sent.

How to Fix the Issue

1. Remove the Auto-Signature from the Draft

Disable Outlook’s automatic signature insertion for messages used as mail merge templates. Instead, start with a clean draft that does not include an auto-inserted signature.

2. Insert a Clean Signature Manually

If a signature is required:

1. Remove the existing signature block entirely from the draft.
2. Recreate or paste a clean HTML signature containing only one image reference.
3. Confirm that the signature block has only a single <img> tag.

3. Avoid Reusing Old Drafts

Start new campaigns from a fresh blank email rather than copying from sent messages or old templates, which often contain hidden embedded images.