Adding a logo to your Outlook signature looks straightforward — click insert, pick an image, save. But anyone who has actually done it knows the pitfalls: the image shows up as a red X for half your recipients, Gmail attaches it as a separate file, the size is twice as large as you wanted, and copying-and-pasting from a signature generator silently breaks everything.

Here’s how to add an image to your Outlook signature correctly in every version, plus the sizing and troubleshooting that determines whether it actually shows up on the other end.

---

1. New Outlook for Windows & Outlook on the Web

The new Outlook desktop app and outlook.office.com share the same signature editor, and signatures sync across both via your Microsoft 365 account.

Add an image to a new or existing signature

1. Click the Settings (gear) icon in the top-right.
2. Select Accounts > Signatures.
3. Click + New signature or select an existing signature to edit.
4. Place your cursor in the signature editor where you want the image.
5. Click the Insert pictures inline icon on the formatting toolbar (mountain icon).
6. Browse to your image file and click Open.
7. The image embeds inline in the signature.
8. Drag a corner handle to resize (drag a side handle and the image stretches).
9. Click Save.

Set as default for new emails and replies

1. Still in Accounts > Signatures, find the Select default signatures section.
2. Choose your signature from the For new messages dropdown.
3. Choose the same (or a different) signature from the For replies/forwards dropdown.
4. Click Save.

Hyperlink the image

1. In the signature editor, click the inserted image once to select it.
2. Click the Insert link icon on the toolbar (chain icon).
3. Paste your destination URL — your website, a booking link, your LinkedIn profile.
4. Click Insert (or OK).
5. Save the signature.

Tip: A hyperlinked logo is the highest-CTR element in most email signatures. Point it at the page you want recipients to act on — usually a booking or scheduling link, not your homepage.

---

2. Classic Outlook for Windows

Classic Outlook stores signatures as local .htm, .rtf, and .txt files in %APPDATA%\Microsoft\Signatures. Images you insert get saved alongside the .htm file in a sibling folder.

Add an image to a new or existing signature

1. Go to File > Options > Mail.
2. Click the Signatures button.
3. In the Signatures and Stationery dialog, select an existing signature or click New to create one.
4. Place your cursor where you want the image.
5. Above the Edit signature box, click the Image icon (small picture frame, second from the right).
6. Browse to your image file and click Insert.
7. Right-click the image and choose Size and Position to set exact dimensions.
8. Click OK twice to save.

Hyperlink the image

1. In the signature editor, click the image to select it.
2. Click the Hyperlink icon (rightmost icon in the signature toolbar) — it looks like a chain.
3. Paste the destination URL in the Address field.
4. Click OK to apply.

Choose default signature

In the Signatures and Stationery dialog, set the dropdowns at the top-right:

• New messages — signature for fresh emails
• Replies/forwards — signature for replies and forwards
• Pick a different signature for each email account if you have multiple.

Note: Classic Outlook has a per-account signature setting. If you use the same signature on all accounts, change the E-mail account dropdown for each account or copy the signature manually.

---

3. Outlook for Mac

Outlook for Mac has its own signature editor.

1. Open Outlook for Mac.
2. Go to Outlook > Settings > Signatures (or Preferences > Signatures on older builds).
3. Click + to create a new signature, or double-click an existing one.
4. In the signature editor, click Picture in the toolbar (or drag the image directly into the editor).
5. Choose your image and click Open.
6. To resize, click the image and drag a corner handle.
7. To hyperlink, select the image, then Edit > Add Link (or Cmd+K).
8. Close the editor to save.

Set the default signature using the Choose default signature section in the same window.

---

4. Outlook for iOS and Android

The mobile Outlook apps support plain text signatures only. You cannot insert an image directly in the mobile signature editor.

Workaround: sync from desktop

Outlook for iOS and Android can pull in your desktop signature via Cloud Settings, which syncs settings across Outlook installations.

1. On your iPhone/Android, open Outlook and tap your profile icon.
2. Tap the gear icon (Settings).
3. Scroll to Settings > Cloud Settings and toggle it on.
4. Sign in to the same account on new Outlook or outlook.office.com.
5. Build your signature with the image there.
6. Within minutes (or after a manual sync), the signature with image syncs to your mobile device.

Plain-text mobile signature

If Cloud Settings doesn’t apply or you want a separate mobile signature:

1. Profile icon > Settings > Signature.
2. Type a short text-only signature (your name, role, link to your website).
3. Tap the back arrow to save.

Note: Even with Cloud Settings, complex HTML signatures sometimes don’t render correctly on mobile. Test by sending yourself an email after enabling the sync.

---

5. Image Sizing Recommendations

Email signature images need to be small — both in pixel dimensions and file size. Recipients open email on tiny mobile screens, slow connections, and metered data.

Recommended dimensions

• Logo (horizontal): max 200px wide × ~60px tall.
• Logo (square or icon): max 100px × 100px.
• Headshot: max 120px × 120px.
• Banner image: max 600px wide × 150px tall (use sparingly — banners are the #1 cause of “your signature looks like spam”).

File size

• Target under 50 KB total per image.
• Hard ceiling 100 KB — beyond that, recipients on mobile data notice.
• Use PNG for logos with transparency, JPG for photos. Avoid GIF unless you’re animating something (and you probably shouldn’t be).

High-DPI displays

If you want a logo that stays sharp on Retina screens, save the source image at 2x dimensions (400px wide for a 200px logo) and let the email client scale it down. Set the display width to 200px in the signature editor — both the desktop apps and most webmail clients will scale appropriately.

---

6. Hyperlinking the Image to a Useful Destination

A logo image is wasted real estate without a link. Best targets, ranked:

1. Booking link — let recipients schedule a meeting in one click.
2. LinkedIn profile — for sales, recruiting, and BD roles.
3. Pricing or product page — if you’re in growth or marketing.
4. Your homepage — fine for branding, but lowest CTR.

To hyperlink the image, see the per-version steps above. After saving, send yourself a test email and click the logo to verify the link works.

Tip: Add a UTM parameter to the link so you can track signature-driven traffic in Google Analytics or PostHog. Example: https://example.com/book?utm_source=email&utm_medium=signature&utm_campaign=outlook.

---

7. Fixing the Red X and Other Common Bugs

”Image shows as a red X”

Cause: The image is linked from a local file path or a URL the recipient can’t access, instead of being embedded as an attachment.

Fix in classic Outlook:

1. File > Options > Mail > Signatures.
2. Edit the broken signature, delete the linked image.
3. Click the Image icon and re-insert via the dialog (Outlook embeds inserted images by default).
4. Save.

Fix in new Outlook / web:

1. Settings > Accounts > Signatures.
2. Edit the signature, delete the broken image.
3. Use the Insert pictures inline button (mountain icon) — never paste from a web page.
4. Save.

”Pasted image disappears or won’t save”

Cause: Pasting from a web page or another email creates a linked image referenced by URL. When you save, Outlook may strip the link.

Fix: Always save the image to your local disk first (right-click > Save image as), then insert it through the signature editor’s image button.

”Recipients on Gmail see my logo as an attachment”

Cause: Gmail’s default behavior is to show inline images both inline AND in the attachments tray for any image embedded as a cid: reference. This is a Gmail rendering decision, not an Outlook bug.

Mitigation:

1. Host the image online (your CDN, an S3 bucket, your website’s /static/ folder).
2. Build the signature HTML manually with a <img src="https://yoursite.com/logo.png"> tag pointing at the hosted URL.
3. Paste the HTML into the classic Outlook signature editor (it accepts HTML when you save the signature .htm file directly in %APPDATA%\Microsoft\Signatures).
4. Recipients now see the image inline only — no attachment.

Trade-off: hosted images get blocked by default in many email clients (“show images” prompt) until the recipient trusts the sender.

”Image looks fine on desktop, broken on mobile”

Cause: The image is too wide for the mobile viewport, or the signature uses a fixed-pixel table that doesn’t reflow.

Fix: Keep logo width at 200px or less. Avoid HTML tables with fixed widths over 320px. Test by sending the email to yourself and reading on your phone.

”Image is too big after I insert it”

Fix in classic Outlook: right-click the image in the signature editor > Size and Position > set exact dimensions.

Fix in new Outlook / web: drag a corner handle (not a side handle) to resize proportionally.

For a logo wider than ~400px in the source file, resize the source image in an image editor (Preview on Mac, Photos or Paint on Windows) before inserting — Outlook’s editor doesn’t compress, so a 2 MB source stays 2 MB in your signature.

---

8. Shared Signatures via OneDrive

If multiple people on your team need the same branded signature, host the signature image on OneDrive or SharePoint and reference it via URL.

1. Upload the logo to a OneDrive folder shared with your team.
2. Right-click the file > Share > Anyone with the link > Copy link.
3. Convert the share link to a direct image URL (replace ?web=1 with ?download=1, or use the embed-friendly format from SharePoint).
4. Build the signature in classic Outlook by editing the .htm file in %APPDATA%\Microsoft\Signatures and pointing the <img src> to the hosted URL.
5. Distribute the .htm file to team members — they drop it into their own Signatures folder.

For larger teams, a third-party signature management tool (Exclaimer, CodeTwo) handles this centrally — but the OneDrive trick works fine for teams under 20 people.

---

Quick Reference

Task	New Outlook & Web	Classic Outlook	Mac	Mobile
Open signature editor	Settings > Accounts > Signatures	File > Options > Mail > Signatures	Outlook > Settings > Signatures	Profile > Settings > Signature
Insert image	Mountain icon	Image icon above editor	Picture in toolbar	Not supported
Hyperlink image	Insert link icon	Hyperlink icon	Cmd+K	N/A
Resize	Drag corner handle	Right-click > Size	Drag corner handle	N/A
Recommended logo size	200px wide, under 50KB	200px wide, under 50KB	200px wide, under 50KB	N/A
Sync to mobile	Cloud Settings	N/A	Cloud Settings	Cloud Settings on

---

Spend Less Time on Email, Period

A polished signature helps your email look professional — but it doesn’t reduce how much email you have to deal with. Carly is an AI assistant that connects to Outlook and 200+ other apps to draft replies, schedule meetings, and clear out the routine messages so you can focus on the ones that matter.

More on Outlook: How to add a signature in Outlook · How to create email template in Outlook · How to set default font in Outlook · How to schedule an email in Outlook · How to set out of office in Outlook · How to share Outlook calendar · How to add a calendar to Outlook · How to save email as PDF in Outlook

Related Articles

Guides

How to Cancel a Meeting in Outlook (Every Version, 2026)

Apr 30, 2026

Guides

How to Clean Up Your Inbox in Outlook (2026)

Apr 30, 2026

Guides

How to Enable Dark Mode in Outlook (Every Version, 2026)

Apr 30, 2026