For advertisers and digital marketers in the know, Gmail Sponsored Promotions (GSP) have become a favorite for cost-effective lead generation and brand awareness since the private beta kicked off a couple years ago.

The big boon here is how GSP approaches native advertising, matching the form and function of the associated platform. That platform is Gmail inboxes–specifically, beneath the Promotions tab. Appropriately, GSP ad units look and behave like the emails beneath them, right down to the brand name and headline filling the subject line and the ability to forward GSPs to your contacts.

Of course, like most relatively new forms of advertising (GSP left beta and opened itself to all advertisers earlier this year), there’s an element of user curiosity and newness here. GSPs appear in a place that’s a natural part of people’s daily lives, a place where they conduct personal business and conversations, and gain a certain credence in doing so. It doesn’t hurt that keyword targeting–interests, brands, products, even competitors–ensures your GSPs feel relevant, timely, and customized.

But the floodgates have opened, and GSP may not be the trump card up a savvy advertiser’s sleeve for much longer. We’ve been a part of the program for a good while now, and the brand awareness value we’ve enjoyed for our clients has been energizing. But we’re also wary of where GSP could go. But first, the good:

Cost-per-click

This is probably the number-one thing we enjoy about GSP (but also the most volative; more on that in a bit). We love telling our clients about the low price of brand awareness and lead generation we get from GSP, and it’s outperforming almost every other avenue in that respect. One of our clients is seeing a cost-per-click for just a handful of cents–30,000% cheaper than what we’re bidding on paid search advertising. That’s a remarkable case, but across the board, CPC with GSP is a fraction of what we’re seeing on other digital media, with the exception of social media. That’s true for another client, whose CPC is only $0.15–a whopping 3400% cheaper than their paid search CPC.

Flexible targeting

But cost-per-click is only an effective or desirable metric insomuch as those users are meaningful and desired. This is where GSP targeting comes into play. We have the ability to target by interest, behavior, and consumer profile on a few platforms (and this comes in extra handy on social media, where that information is openly collected), but in Gmail, these factors are accurately represented by keywords.

It’s simple in theory but powerful in practice. Are your desired customers talking about a competitor? A product? A recent news story? A phase or major event in their lives? Chances are, they’ve sent or received email involving these things. A note from a co-worker, perhaps, or a newsletter from a valued website, or a reminder from a family member about a shopping list. The permutations are endless, but if your desired audience is talking about something, it’s a keyword, and those keywords are your ticket into their inboxes. It’s an assurance that the user you reach are important and, in some way, interested in what you’re saying or selling.

High intent

The way keywords are matched to user activity doesn’t just ensure you’re reaching the right folks; it makes every website click a bit more meaningful. There are a couple reasons why. Gmail users skew a bit younger and tech-savvier, and are probably more aware that your ad unit is a paid placement. This means some of the clicks through to your website or content reflect not only an interested party, but a party that’s aware you’re paying to enter their personal inbox–and felt empowered to click through anyway.

There are multiple steps to a website click, as well. The user has to click on your teaser ad, with a 50×50 image and up to 125 characters of text, first. This opens a rich HTML unit (up to 600×1000). A second click through this unit to your landing page or content represents high user intent: they’re interested in your product (or they wouldn’t be seeing your ad), and they found your messaging and/or brand compelling enough to warrant breaking away from personal matters through two clicks of discovery.

This intent is evident in Analytics, too. We’re seeing 25% of leads stay on our client websites for a minute or longer, and 80% of traffic is mobile. Think about that. Your lead’s phone is out. They’re going about their busy lives, flitting between activities, aimlessly checking email or popping in for a quick glance. In today’s world of fleeting, schizophrenic consumption, we’d be pleased if just a handful of people spent more than a minute on our pages in those conditions. But it’s happening every day.

Share the love

Finally, we love how GSPs include a couple familiar user features that make them feel more like real emails. For one, users can “Save” your promotion in the same way they might favorite an email. Going one step further, they can “Forward” your promotion to contacts in the same way they might forward a funny anecdote or Share a Facebook post. It’s a chance for free impressions and clicks, but also a built-in feature for brand identification. Your messaging can (and should) compel the initial viewer to find some aspect of themselves reflected in your brand. If they do, self-identification might be what pushes your promotion to their trusted contacts.

…But not for long

We’re skeptical that advertisers will enjoy exceptional, anomalous results from GSP for too much longer. For our client industries, we’ve been able to draw comparisons between the widespread settling of paid search advertising and the recent opening of GSP to all advertisers. Specifically, cost-per-click is rising as more advertisers enter the market. With GSP integrating directly with AdWords earlier this week, it’s only going to get more competitive.

For now, the results we’re seeing are well worth it from a brand awareness and lead generation perspective. But, as with all forms of promotion, it’s important to consider just how much brand awareness (a notoriously vague objective) is worth. As more and more promotions are sent out and consumers grow accustomed to their presence, user intent will trend upward, but at what point does cost-per-click negate the benefit?

The decision will be different for every company, industry, and budget. It’s more important than ever for companies to work with digital marketing professionals who understand this balance and constantly examine the program for ROI and optimization–even cancellation, if the marketing dollars are better spent elsewhere.

For more advertising insights, read our 5 insider tips on Facebook advertising straight from Facebook itself and an update on what Google’s Art, Copy, and Code team is up to.