Email Signature Banners in Gmail: Sizes, Examples and Running Campaigns

An email signature banner is a small clickable image under your signature that promotes one thing: an event, a launch, a hiring push. For Gmail, we recommend designing it at 400 x 100 pixels, the top of Google’s recommended signature image range, and linking it with UTM tags so visits show up in Google Analytics.

In Google Workspace, Patronum adds a banner to every user’s Gmail signature from one template, or a different banner per OU or Google Group, with UTM codes so banner visits show up in Google Analytics.

Email signature banner size

Recommendation: 400 x 100 pixels. Google’s Gmail Help recommends a signature image 70 to 100 pixels high by 300 to 400 pixels wide, and states that “The maximum size for email signature images is 100 pixels high by 1000 pixels wide” (Gmail Help). A 400 x 100 banner uses the full recommended range without going past it.

Treat that as practical guidance, not a tested rule. Google publishes the figures; we haven’t checked whether Gmail rejects, shrinks or simply displays a larger image. Many design templates use 600 x 150, which is taller than Google’s stated maximum, so resize those before use.

Three file rules:

• PNG or JPG, not SVG. Patronum’s help center says “it is not possible to embed SVG images into your email signatures” (Patronum Help).
• Keep it light. Google states a 10,000-character limit for Gmail signatures, and “Your image also counts toward the character limit” (Gmail Help).
• Set the display size in the HTML (width="400" height="100"). Whether to export at 2x for sharper screens is a trade-off; our email signature image size guide covers it.

5 email signature banner examples

Each banner asks for one click, with one line of large text and space at the edges so it doesn’t crowd the signature. They use a fictional company, Harbor & Pine. The links follow the tagging scheme in the next section.

1. Event (shown above)
Alt text: “Meet Harbor & Pine at Booth 214, Austin, May 12 to 14”
Link: example.com/events?utm_source=email_signature&utm_medium=email&utm_campaign=expo_may&utm_content=booth_navy

2. Webinar

Alt text: “Register for the Harbor & Pine live demo, Thursday 11 a.m. ET”
Link: example.com/webinar?utm_source=email_signature&utm_medium=email&utm_campaign=demo_webinar&utm_content=thursday_blue

3. Product launch

Alt text: “See what’s new in Harbor Track”
Link: example.com/track?utm_source=email_signature&utm_medium=email&utm_campaign=track_launch&utm_content=launch_green

4. Hiring

Alt text: “View open support engineer roles at Harbor & Pine”
Link: example.com/careers?utm_source=email_signature&utm_medium=email&utm_campaign=hiring_q4&utm_content=support_sand

5. Reviews

Alt text: “Leave Harbor & Pine a review”
Link: example.com/review?utm_source=email_signature&utm_medium=email&utm_campaign=reviews&utm_content=stars_blue

Write alt text as a call to action, since that’s all some recipients will see. Gmail can hide images until the reader opts in (Gmail Help), and classic Outlook “is configured by default to block automatic picture downloads from the Internet” (Microsoft Support). A one-line text link under the banner is a good backup.

Banner campaign tracking with UTM parameters

Use the same three fixed values on every banner link and change the rest per campaign:

Parameter	Value	Why
utm_source	email_signature	Separates signature traffic from newsletters and other email
utm_medium	email	Puts the visits in Google Analytics’ Email channel
utm_campaign	One per campaign, e.g. expo_may	Compares campaigns
utm_content	One per design, e.g. booth_navy	Google describes it as a way “to differentiate creatives”

Google Analytics recommends you “always use utm_source, utm_medium, and utm_campaign,” and values are case sensitive (Google Analytics Help), so pick lowercase and stick to it.

Why email and not banner? In Google Analytics’ default channel group, a medium of “banner” is one of the values that defines the Display channel, while a medium of “email” defines Email (Google Analytics Help). Tag a signature banner with utm_medium=banner and its visits get reported alongside display ads.

Know what the numbers mean. Tagged links attribute website visits and conversions to the banner. They aren’t a count of every banner click: Google Analytics only sees a click that turns into a recorded visit on a page running your analytics, so visitors whose browsers block tracking or who leave before the page loads won’t appear. Read the figures as a trend for comparing campaigns, not as a full click total.

How to add a banner to company email signatures in Google Workspace

Gmail has no separate banner setting. A banner is a linked image inside the signature. Google lists three ways to manage signatures centrally: the Append footer setting, the Gmail API, and Workspace Marketplace apps (Google Workspace Admin Help). For a few people, each user can add the image in Gmail’s own signature settings. Past that, someone forgets the tag, and the banner outlives the campaign in 40 signatures.

With Patronum, the banner lives in the HTML signature template:

1. Host the image publicly. If it’s in Google Drive, “the image sharing settings must be set to public” (Gmail Help). Avoid intranet servers: Google warns that “links to images that are dependent on internal IPs and sometimes cookies are broken” behind its image proxy (Google Workspace Admin Help).
2. Add the banner to the template as a linked image with alt text and the tagged URL. Patronum’s help center notes that “any URLs containing your domain will be automatically converted to a trackable link which you can monitor within Google Analytics” (Patronum Help), so check the link Patronum produces before adding your own tags twice.
3. Scope the policy. A signature policy can target all users, an organizational unit, or a Google Group (Patronum Help). Sales can carry the webinar banner while support carries the review banner.
4. Activate and wait. Patronum syncs signature policies to Gmail hourly through the Gmail API, and Gmail may cache signatures for 1 to 2 hours. If a user edits their signature, the policy overwrites the change on the next sync (Patronum Help).
5. End the campaign on time. Patronum doesn’t document a banner scheduler, so put the end date in your calendar and swap the banner in the template. If you need scheduling, A/B tests or click dashboards inside the tool, marketing-led tools are stronger here: Exclaimer includes campaign management on its Standard and Pro plans and engagement dashboards on Pro (Exclaimer pricing).

After the first sync, check:

• Compose a new message as a user in each targeted OU or group and confirm the right banner appears.
• Click the banner and confirm the landing page URL still carries your UTM tags, then check Google Analytics’ realtime report for a visit with your source and medium.
• Send to an outside address with images blocked and confirm the alt text reads as a call to action.
• Reply from Gmail on Android. Since April 2025, Gmail on Android uses the web signature when no mobile signature is set, with “support for images, logos, and text formatting” (Google Workspace Updates), so banners may appear in mobile replies.
• Make sure the landing page delivers what the banner promised. Google’s sender guidelines say “Recipients should know what to expect when they click a link” (Gmail Help).

See how Patronum manages Gmail signatures, or pair a banner with one of our business email signature templates . For the logo side, read how to add a logo to a Gmail signature .

Sources

• Gmail Help, signature image size and troubleshooting: https://support.google.com/mail/answer/11468381?hl=en
• Gmail Help, create a Gmail signature (10,000-character limit): https://support.google.com/mail/answer/8395?hl=en
• Gmail Help, images in Gmail: https://support.google.com/mail/answer/145919?hl=en
• Gmail Help, email sender guidelines: https://support.google.com/mail/answer/81126?hl=en
• Google Workspace Admin Help, user signatures in Gmail: https://knowledge.workspace.google.com/admin/gmail/set-up-google-workspace-user-signatures-in-gmail
• Google Workspace Admin Help, image URL proxy allowlist: https://knowledge.workspace.google.com/admin/gmail/advanced/set-up-an-image-url-proxy-allowlist
• Google Workspace Updates, release notes 4 April 2025 (Android signatures): https://workspaceupdates.googleblog.com/2025/04/release-notes-04-04-2025.html
• Google Analytics Help, collect campaign data with custom URLs: https://support.google.com/analytics/answer/10917952?hl=en
• Google Analytics Help, default channel group: https://support.google.com/analytics/answer/9756891?hl=en
• Microsoft Support, picture downloads in classic Outlook: https://support.microsoft.com/en-us/office/block-or-unblock-automatic-picture-downloads-in-classic-outlook-email-messages-15e08854-6808-49b1-9a0a-50b81f2d617a
• Exclaimer, pricing (read 13 October 2026): https://www.exclaimer.com/pricing
• Patronum Help Center, creating a policy: https://help.patronum.io/en/article/creating-a-policy-jmctey/
• Patronum Help Center, manage multiple Gmail signatures: https://help.patronum.io/en/article/manage-multiple-gmail-signatures-8bua8j/
• Patronum Help Center, Google Analytics in email signatures: https://help.patronum.io/en/article/adding-google-analytics-to-email-signatures-r2l7fq/
• Patronum Help Center, embedded images not showing: https://help.patronum.io/en/article/embedded-images-not-showing-in-email-signature-1kn49u7/

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Writer notes (not for publishing):

Revision changes (14 Oct):
– UTM guidance corrected: utm_medium=email, utm_source=email_signature, utm_content per design. Verified by WebFetch 13 Oct 2026 against GA default channel group (support.google.com/analytics/answer/9756891): Display = medium one of “display”, “banner”, “expandable”, “interstitial”, “cpm”; Email = source or medium email|e-mail|e_mail|e mail. utm_content wording (“Use to differentiate creatives”) verified on answer/10917952. All five example links updated.
– Added a paragraph explaining tagged links attribute visits/conversions, not a full click count. The reasons given (blocked tracking, leaving before the page loads) are general analytics behavior, not a Google quote.
– 400 x 100 now framed as “our recommendation” grounded in Gmail Help 11468381 (re-verified 13 Oct 2026), with an explicit line that we haven’t tested enforcement. The pending test now also covers a taller image.
– Five actual banners designed and rendered (img/slot15-banner-1 to 5.png, 400 x 100 display, 2x PNG via Playwright/Chromium, fictional Harbor & Pine brand and mark). Banner 1 is the hero under the intro. Banner 3 copy changed to “Meet Harbor Track / Live tracking for fleet teams” to fit one line.
– Clear separate sections: size, examples, campaign tracking, rollout. Cut the four-row size comparison table, the Exclaimer size paragraph, the “Where people get banners wrong” section (its size point repeated the size section; alt text, mobile and link-promise points moved to where they apply) and the FAQ (all three questions were answered in the body).
– New practical point from S34: Patronum auto-converts links on your domain to trackable links, so readers should check the produced link before adding tags twice. Exact behavior (which parameters Patronum adds) unconfirmed; ask Paul (Q1).
– Ending is now deploy steps plus a post-sync verification checklist.
– 2x export: the article no longer tells readers to export at 2x (Patronum’s two help articles disagree, and the published image-size guide advises against resizing via HTML); it links to that guide for the trade-off. The PNGs in this article are 2x renders for blog display only.
– Not applied: none of the review points were skipped.
– Body word count after revision: about 1,250 excluding meta, image alt text, link code and sources.

• Patronum fact IDs relied on: S3, S4 (hourly sync, Gmail cache), S11 (scope), S32 (no SVG), S34 (UTM, auto-converted trackable links), S36 (no in-app dashboard, worded as absence of documentation), S37 (overwrite on next sync).
• Not claimed: banner module, scheduling, rotation, A/B testing, in-app click analytics, mobile app deployment.
• Exclaimer plan claims from 13 Oct 2026 read; need Paul’s comparison sign-off.
• Placeholders: one IMAGE PLACEHOLDER (E category: banner in a real Gmail message, images on and blocked) and one FIRST-HAND TEST PENDING.
• Internal links: /email-signature-image-size and /email-signature-management live; article 8 and article 13 marked LINK LIVE AFTER PUBLISH.
• Image files: drafts/img/slot15-banner-*.png (render script in scratchpad/render/). Upload with the article.
• Paul questions affecting this: Q1 (banner/campaign feature, what S34’s auto-conversion adds), Q3 (sync wording), Q5 (mobile).
• Carve-out: signature article, not counted toward the 35/75 Ground Floor.