BLOG - Passendo vs Google Ad Manager for Email Ad Serving
Publishers looking for a Google Ad Manager alternative for email tend to find their way to Passendo for a simple reason: Passendo was built specifically for email, from the ground up, with the constraints and commercial logic of the email channel informing every product decision.
That’s the core architectural difference between the two platforms, and it shapes everything that follows in this comparison.
GAM is a web-first ad server. When Google added email newsletter ad support in 2024, it was a logical extension of an existing platform, but it arrived as a beta feature, available only to enterprise-tier GAM 360 customers, and it covers a deliberately narrow slice of what a commercial email monetisation programme actually requires.
Passendo, by contrast, has no web-first legacy to work around. The waterfall logic, the programmatic exchange, the SOV delivery mechanics, all of it was designed with email’s specific constraints in mind.
This comparison covers both platforms honestly, including the limitations that are inherent to the email channel and apply equally to both. Where they diverge, the differences are structural.
Access and availability: who can actually use GAM for email
The first practical question is about whether GAM’s email support is available to you at all.
Dimension | Passendo | Google Ad Manager |
Design intent | Purpose-built for email — ad serving logic designed around email constraints from day one | Web-first platform — email newsletter ads is a Beta add-on (GAM 360 only) |
Availability | Standalone SaaS — accessible to publishers of any scale | GAM 360 (enterprise tier) only — requires a Google account manager relationship |
Impression counting | Request-based (channel constraint — same as GAM) | Request-based (channel constraint) |
GAM’s email newsletter support is exclusively available on GAM 360, the enterprise tier that requires an active Google account manager relationship. For the majority of independent publishers and newsletter operators, the feature is simply not accessible.
Passendo is a standalone SaaS platform – no enterprise relationship required, no minimum spend threshold, available to publishers at any scale.
On impression counting, both platforms are equal, and for the same reason. Request-based counting is a channel constraint, not a platform choice. Neither Passendo nor GAM can reliably confirm ad rendering in email the way JavaScript enables on the open web.
Ad selection and monetisation: one demand layer vs. a full stack
This is where the commercial gap between the two platforms becomes most tangible, and where publishers on GAM’s email feature most commonly hit a ceiling.
Dimension | Passendo | Google Ad Manager |
Ad selection & waterfall | Full priority waterfall: guaranteed → programmatic → house. SOV delivery, pacing, dynamic allocation across demand tiers | Reservation and Programmatic Guaranteed only. No waterfall, no remnant programmatic, no dynamic allocation |
Share of Voice (SOV) | Fully supported — % of impressions across competing advertisers | Basic % goal via Sponsorship line item only — no multi-tier SOV logic |
Open programmatic fill | Own email ad exchange fills unsold inventory — publishers monetise remnant | Not supported — no open auction for email inventory |
Passendo DSP access | Single toggle inside the ad server — direct access to DSP demand | Not applicable |
GAM’s web platform supports a rich ad selection hierarchy – sponsorships, standard line items, open auction – but none of this applies to email inventory.
In GAM’s email environment, publishers have one demand layer: sell a direct deal, or serve a house ad. There is no open programmatic auction, no waterfall logic, no remnant monetisation, no dynamic allocation. Unsold inventory goes to a house ad, and that’s the end of the line.
Passendo was built to solve exactly this problem.
The full monetisation stack it supports includes:
- A complete priority waterfall — guaranteed deals, programmatic exchange, and house ads in the correct commercial order
- Share of Voice (SOV) delivery for sponsorship campaigns, where an advertiser books a percentage of impressions across a newsletter audience
- Passendo’s own email ad exchange, providing open programmatic demand to fill inventory that would otherwise go blank
- Passendo DSP — accessible via a single toggle inside the ad server, adding a further direct programmatic demand layer
The practical outcome is straightforward: publishers on Passendo monetise inventory that publishers on GAM’s email feature cannot. Every send with unsold inventory is a revenue opportunity with Passendo that GAM leaves on the table.
Creative formats, ESP compatibility, and channel constraints
Some limitations in email ad serving are not platform choices, they’re characteristics of the channel itself. It’s worth being clear about which is which.
Dimension | Passendo | Google Ad Manager |
Creative formats | Image banners + native ad formats | Image only — no native, no rich media |
Geo/device targeting | Unreliable due to email proxies & Apple MPP (channel constraint) | Unreliable due to email proxies & Apple MPP (channel constraint) |
Merge tag setup | Required (channel requirement) | Required (channel requirement) |
ESP compatibility | Broad — wide range of ESPs supported with dedicated onboarding support | Limited — only a handful of major ESPs officially documented |
Geo and device targeting are unreliable on both platforms due to Gmail’s image proxy infrastructure, Apple Mail Privacy Protection, and similar caching behaviour across major email clients. Merge tag setup is required by both – it’s a channel requirement for generating unique per-recipient ad requests, not a Passendo or GAM quirk. Neither platform has an advantage here, and any comparison that pretends otherwise isn’t being straight with you.
Where the platforms differ: GAM’s email support is image banners only: no native formats, no rich media.
Passendo supports both image banners and native ad formats, which matters for publishers whose editorial environment makes hard-edged display units a poor fit for their audience.
ESP compatibility is another practical divergence. GAM documents a limited set of major ESPs. Passendo supports a broad range of ESPs, with dedicated human onboarding for integration and tagging, not a help centre article.
Ad blocking and domain reputation
GAM’s email tags route through securepubads.g.doubleclick.net, one of the most widely blocked ad-serving domains in existence.
Passendo’s infrastructure doesn’t carry that domain-level risk. For publishers where fill reliability and deliverability matter, this is a real operational difference, not a theoretical one.
Support: self-serve vs. human-led
GAM and Passendo take fundamentally different approaches to publisher support, and the gap is significant for anyone setting up email ad serving for the first time.
Dimension | Passendo | Google Ad Manager |
Human support | Full human support for all clients — onboarding, tagging, troubleshooting | Self-serve documentation and community forums; no dedicated email ad serving support |
Google dependency | None — independent, publisher-aligned platform | Full — demand, policies, billing, and ecosystem all within Google’s stack |
GAM is self-serve. Email-specific issues – tagging, ESP integration, delivery troubleshooting – are handled through documentation and community forums. There is no dedicated human support for newsletter ad serving, which means when something goes wrong in a channel GAM treats as a beta add-on, you’re largely on your own.
Passendo provides full human support for every client, from initial setup through ongoing campaign management. For publishers without a dedicated ad operations team — which is most newsletter publishers — this is often the difference between a working integration and one that stalls before the first campaign goes live. For publishers migrating from GAM specifically, Passendo’s onboarding team manages the transition directly.
Which platform fits which publisher - and why publishers switch
GAM’s email feature works well in a specific scenario: a GAM 360 publisher running direct-sold campaigns only, with no interest in monetising unsold inventory and no need for waterfall logic. If you’re already embedded in Google’s ecosystem and your email programme is small and direct-sold, GAM may be sufficient.
For any publisher with a genuine commercial email programme, or ambitions to build one, the ceiling arrives quickly.
The publishers who move to Passendo from GAM aren’t doing so for marginal reasons. They’re doing it because GAM’s email feature cannot support a full monetisation strategy, and the revenue impact of that gap compounds with every send.
The switch to Passendo typically unlocks three things at once: unsold inventory that was previously going blank starts generating programmatic revenue; SOV and waterfall logic allows publishers to run more sophisticated guaranteed campaigns alongside remnant fill; and having a platform and team purpose-built for email means the operational overhead of running an email ad programme drops significantly. For most publishers, the ROI case is straightforward.
If you’re evaluating email ad serving platforms or considering a move from GAM, Passendo’s team will walk you through what setup and migration look like for your specific programme.
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