SOI vs DOI Offers: Single vs Double Opt-In Explained

SOI (Single Opt-In) and DOI (Double Opt-In) are two types of CPA offer conversion flows that differ in how many steps the user must complete. SOI requires the user to submit their information once — typically entering an email address or filling out a short form — with no additional verification. DOI requires the same initial submission plus a second verification step, usually clicking a confirmation link sent to their email. The distinction matters because it directly affects conversion rates, payouts, and traffic quality.

Why SOI vs. DOI Matters

Understanding the difference between SOI and DOI is essential for publishers because it affects every aspect of campaign performance:

• Conversion rates — SOI offers convert at much higher rates because there's no second step. DOI adds friction (users must check their email and click a link), so a significant percentage of users drop off.
• Payouts — DOI offers pay more per conversion because the lead is verified and higher quality. Advertisers are willing to pay a premium for confirmed email addresses.
• Traffic strategy — SOI offers work well with incentivized traffic and high-volume sources. DOI offers perform better with engaged, intent-driven traffic.
• EPC impact — Despite lower payouts, SOI offers often produce comparable or higher EPCs than DOI because of their dramatically higher conversion rates.

How SOI Works

1. The user clicks a tracking link and lands on the offer page.
2. The user enters their email address (and possibly name or ZIP code).
3. The user clicks "Submit" or "Sign Up."
4. The conversion fires immediately — the publisher earns their commission.

That's it. One step, one submit, one conversion. The simplicity is what makes SOI offers convert so well — there's nothing else for the user to do.

How DOI Works

1. The user clicks a tracking link and lands on the offer page.
2. The user enters their email address (and possibly other information).
3. The user clicks "Submit" or "Sign Up."
4. The system sends a confirmation email to the address provided.
5. The user opens the email and clicks the confirmation link.
6. Only now does the conversion fire — the publisher earns their commission.

The extra step (email confirmation) is where DOI loses conversions. Industry data suggests that 30-50% of users who complete step 3 never complete step 5 — they either don't check their email, can't find the confirmation (it landed in spam), or simply lose interest.

SOI vs. DOI: Head-to-Head Comparison

Factor	SOI (Single Opt-In)	DOI (Double Opt-In)
Steps to convert	1 (submit form)	2 (submit form + email confirmation)
Typical payout	$0.50 – $3.00	$1.50 – $6.00
Conversion rate	15-40%+	5-15%
Lead quality	Lower — unverified email, higher fake/typo rate	Higher — confirmed real email address
Best traffic types	Incent, offerwalls, content lockers, social, push	SEO, email, content sites, non-incent
EPC range	$0.10 – $0.50	$0.10 – $0.50
Scrub rate	Higher (more fake/invalid emails)	Lower (email is verified)
Best for beginners?	Yes — easier to generate conversions	Moderate — requires quality traffic

Notice that the EPC ranges overlap significantly. Even though DOI pays more per conversion, the lower conversion rate often brings the EPC back to similar levels as SOI. The right choice depends on your traffic source and strategy, not just the payout number.

Common SOI/DOI Verticals

SOI Offers (Popular Verticals)

• Sweepstakes — "Enter to win an iPhone!" — user submits email to enter. The most classic SOI offer type.
• Newsletter signups — Subscribe to a deals newsletter, finance newsletter, or lifestyle content.
• Free trial registrations — Create an account for a free service (no credit card required).
• Quiz/survey funnels — User answers a few questions and submits their email for results.

DOI Offers (Popular Verticals)

• Email marketing lists — Premium newsletter subscriptions where the advertiser needs verified, deliverable email addresses.
• Financial services — Sign up and verify for budgeting tools, investment platforms, or banking apps.
• Subscription services — Verify email to activate a free trial for streaming, software, or content platforms.
• Health and wellness — Confirm interest in health products, supplements, or wellness programs.

Optimizing SOI Campaigns

• Volume is your friend — SOI's strength is high conversion rates. Focus on driving volume to maximize total earnings.
• Use on offerwalls and content lockers — SOI offers are perfect for offerwalls and content lockers because users can complete them in seconds.
• Watch your scrub rate — Since SOI doesn't verify emails, advertisers may scrub conversions with obviously fake emails. Monitor your scrub rate and encourage users to use real information.
• Test multiple offers — SOI offers in the same vertical can have very different EPCs. Run A/B tests with at least 200 clicks per offer before deciding.

Optimizing DOI Campaigns

• Pre-frame the confirmation step — On your pre-sell page or content, tell users: "Check your email and click the confirmation link to complete your signup." Setting this expectation reduces drop-off.
• Target engaged audiences — DOI works best with users who genuinely want the product. SEO traffic, email subscribers, and content readers are ideal.
• Avoid incent traffic for DOI — Incentivized users often skip the email confirmation step because they've already moved on. If you're running incent traffic, stick to SOI.
• Monitor email deliverability — If the confirmation email consistently lands in spam, your DOI conversion rate will plummet regardless of traffic quality. Report delivery issues to your account manager.

Example: SOI vs. DOI with the Same Traffic

Scenario: You send 1,000 clicks from your finance blog to two similar sweepstakes offers — one SOI, one DOI.

Metric	SOI Offer	DOI Offer
Clicks sent	1,000	1,000
Payout	$1.50	$3.50
Conversion rate	22%	8%
Conversions	220	80
Total earnings	$330	$280
EPC	$0.33	$0.28

In this example, the SOI offer produces a higher EPC despite paying less than half per conversion. The dramatically higher conversion rate more than compensates for the lower payout. However, results vary by traffic source — DOI can outperform SOI with high-intent, non-incent traffic.

Related Terms

• CPA (Cost Per Action) — The pricing model that SOI and DOI offers use
• EPC (Earnings Per Click) — The key metric for comparing SOI and DOI offer performance
• Incentivized Traffic — Traffic type that works especially well with SOI offers
• Scrub Rate — Conversion rejection rate, typically higher for SOI than DOI
• CPL (Cost Per Lead) — Lead generation model closely related to SOI/DOI conversion flows