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Tag your email links so the clicks add up.

Q: What utm_source and utm_medium should I use for email?

Use utm_medium=email for every email link — that is the value GA4 recognises for the Email channel. For utm_source, name the email program or list, not the tool: newsletter, welcome-series, or your brand name work well. Keep both lowercase. Avoid utm_medium=newsletter or utm_medium=mailchimp; GA4 reads the medium to bucket the channel, so anything other than email can land your clicks in Unassigned.

Q: Does Mailchimp add UTM parameters automatically?

Yes. Mailchimp's Google Analytics link tracking, when enabled, appends UTMs to every link in the campaign — utm_medium=email, with utm_source and utm_campaign both set to the campaign title by default. The catch is that the campaign title is often messy, so it becomes a messy UTM, and if you also add UTMs by hand you get the parameter twice. Pick one: let Mailchimp tag and name the campaign cleanly, or turn its tracking off and tag links manually — never both.

Q: How do I track which link in an email was clicked?

Vary utm_content per link. If every button and text link in the email carries the same UTMs, GA4 shows one row and you cannot tell the header CTA from the footer link. Give each placement its own utm_content value — utm_content=header-cta, utm_content=product-1, utm_content=footer — and the clicks split out by what people actually pressed.

Q: Should I shorten the tagged link in my email?

It helps. A fully tagged URL is long and ugly in an email, can wrap awkwardly in plain-text versions, and a wall of utm_ parameters can nudge spam filters. A short link keeps the visible URL clean while the UTMs ride along on the destination, and a slsh.me short link also logs every click by country and device — a second, tool-independent count next to your ESP's open-and-click stats.

Send a newsletter or a campaign blast and you want every click attributed to email — not lumped under "direct" or split across mismatched rows. Here are the exact source and medium values for email, how Mailchimp and Klaviyo auto-tag, and a copy-paste template.

Updated June 28, 2026 · by slsh.me

The short answer

Medium is always email; source is the list or program.

source newsletter medium email campaign march-product-update

Set utm_medium=email on every link — that's the value GA4 maps to the Email channel — and use utm_source to name the program (newsletter, welcome-series, your brand). Keep every value lowercase and hyphenated so GA4 reports one clean row per send instead of a scatter of near-duplicates.

Want it right before you hit send? Build the parameter string with the free slsh.me UTM builder — it lowercases and encodes as you type — then drop a slsh.me short link into the email so the destination stays clean and every click lands in your dashboard. Already shipped a send? Paste a link from it into the UTM parser to check the tags.

The right values per parameter.

Five UTM parameters, mapped to what an email send should put in each one. Medium and source are the two that decide whether GA4 files the click as Email.

Parameter	Use for email	Why
`utm_medium`	`email`	The channel type. GA4 buckets `email` into the Email channel — not Unassigned.
`utm_source`	`newsletter`, `welcome-series`, brand	Which list or program sent it. Name the audience, not the tool.
`utm_campaign`	`march-product-update`	The specific send or series. Same scheme as the rest of your campaigns.
`utm_content`	`header-cta`, `footer`	Which link in the email drove the click. Vary it per placement.
`utm_term`	leave blank	Reserved for paid-search keywords. Email doesn't need it.

One decision to make up front: what goes in source. Name the audience or program — newsletter, onboarding, customers — rather than the sending tool. Putting mailchimp or klaviyo in source ties your reports to a vendor you might switch, and tells you nothing about who you emailed. Whatever you pick, apply it consistently — a mix of newsletter, Newsletter and news fragments the source exactly the way GA4 splits casing. (More on that in the UTM naming convention guide.)

Let your ESP tag — or tag by hand, not both.

Most email platforms can append UTMs for you. The trap is doing it twice. Pick one method and stick to it across every send.

Platform	Auto-tagging	What to watch
Mailchimp	"Google Analytics link tracking" toggle, per campaign	Sets `utm_source` and `utm_campaign` to the campaign title — name it cleanly, or the title becomes your messy UTM.
Klaviyo	On by default; UTM settings per flow/campaign	Default `utm_source=klaviyo` — change it to your program name so reports don't read as the tool.
Campaign Monitor / others	Usually a tracking toggle	Confirm the medium it writes is `email`, and that it isn't also appending to links you tagged by hand.
Plain / transactional	None — you add UTMs manually	Use the copy-paste template below, or build links one-by-one.

The catch with auto-tagging: if the platform appends UTMs and your links already carry them, you end up with ?utm_source=a&utm_source=b — duplicate parameters where the last one wins, often silently overwriting the value you intended. Decide once: either turn the ESP's tracking on and never hand-write UTMs in that send, or turn it off and own the tags yourself. Owning them by hand gives you clean, descriptive sources and per-link utm_content — worth it for anything you want to attribute precisely.

The copy-paste template.

Append this to the destination URL of a link in your email. One ?, parameters joined by &, all lowercase.

# Newsletter link — append to the destination URL
https://example.com/landing?utm_source=newsletter&utm_medium=email&utm_campaign=march-product-update&utm_content=header-cta

Change utm_content for each link in the email (header-cta, product-1, footer) so you can see which one was pressed. Keep utm_source and utm_campaign identical across every link in the same send. If your ESP auto-tags, don't paste this on top of it — that's the double-tagging trap above.

The mistakes that break attribution.

Four things that quietly send your email clicks to the wrong place in GA4.

Using `newsletter` or `mailchimp` as the medium

GA4's channel grouping reads utm_medium. A medium of newsletter or mailchimp isn't recognised, so the traffic falls into Unassigned.

Fix: always use utm_medium=email; put the program name in utm_source instead.

Double-tagging with the ESP

Letting Mailchimp or Klaviyo auto-append UTMs and adding them by hand produces utm_source=a&utm_source=b — the value you wanted gets overwritten.

Fix: pick auto or manual for each send, never both.

The same `utm_content` on every link

If the header CTA, the product links and the footer all share one utm_content, GA4 shows a single row and you can't tell what people clicked.

Fix: give each link its own utm_content (header-cta, footer…).

Capitals and spaces in values

March Update becomes March%20Update — a capitalised, encoded value that won't match march-update elsewhere in your reports.

Fix: write every value lowercase-with-hyphens from the start.

Build the string without typos.

The hard part of email UTMs isn't the medium — it's keeping utm_source and utm_campaign identical across a dozen links while only utm_content changes. Build the shared part once from a form that lowercases and encodes for you, then vary the content value per link.

The free slsh.me UTM builder lays out every parameter, normalises casing and spacing as you type, and shows the finished string — so every link in your email ships with identical, GA4-friendly source and medium values.

Build your email UTMs, free

Then shorten the destination on slsh.me — a clean short link in the email keeps the long tagged URL out of sight and logs every click by country and device, free.

Questions

What utm_source and utm_medium should I use for email? +

Always utm_medium=email — that's the value GA4 recognises for the Email channel. For utm_source, name the email program or list (newsletter, welcome-series, your brand), not the sending tool. Keep both lowercase. Avoid utm_medium=newsletter or utm_medium=mailchimp, which land your clicks in Unassigned.

Does Mailchimp add UTM parameters automatically? +

Yes — its "Google Analytics link tracking" toggle appends UTMs to every link in the campaign. The catch is it sets utm_source and utm_campaign to the campaign title, so name the campaign cleanly. And if you also tag links by hand you'll double up. Pick one: let Mailchimp tag, or turn it off and tag manually — never both.

How do I track which link in an email was clicked? +

Vary utm_content per link. If every button and text link carries the same UTMs, GA4 shows one row. Give each placement its own value — utm_content=header-cta, utm_content=product-1, utm_content=footer — and the clicks split out by what people actually pressed.

Should I shorten the tagged link in my email? +

It helps. A fully tagged URL is long and ugly, wraps awkwardly in plain-text versions, and a wall of utm_ parameters can nudge spam filters. A short link keeps the visible URL clean while the UTMs ride along on the destination — and a slsh.me link logs every click by country and device. See the reading UTM data in GA4 guide.

Every email click, accounted for.

Shorten the links in your newsletter with slsh.me. The long tagged URL hides behind a tidy short link, and you get live click analytics per link — by country, device and referrer, free.

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