Best Email Deliverability Tools for Klaviyo: Mailmend.io vs GlockApps

For e-commerce brands using Klaviyo, inbox placement determines email revenue. While GlockApps provides comprehensive diagnostic testing across multiple email providers, Mailmend delivers what testing tools cannot: algorithmic technology that actively moves promotional emails from Gmail's Promotions tab to the Primary inbox. Understanding this fundamental difference—between identifying deliverability problems and actually solving them—helps seven-to-eight-figure e-commerce brands select the approach that generates measurable revenue impact rather than just diagnostic reports.

Key Takeaways

• Mailmend delivers up to 100%+ email revenue increases through proprietary algorithmic inbox placement, while GlockApps provides diagnostic testing that identifies issues without fixing them

• E-commerce brands achieve results within 24 hours using Mailmend's drag-and-drop Klaviyo integration versus weeks of manual optimization based on GlockApps testing data

• Mailmend requires zero content changes—no copywriting adjustments, design modifications, or strategy overhauls—while traditional deliverability approaches demand comprehensive email revamps

• GlockApps tests inbox placement across 20+ email service providers but cannot address Gmail's Promotions tab categorization algorithm, the primary challenge for e-commerce marketers

• Mailmend's native Klaviyo integration enables direct A/B testing to measure exact revenue lift, while GlockApps operates externally through seed list testing

• For Black Friday, product launches, and seasonal campaigns, Mailmend's same-day implementation outperforms warmup-based approaches requiring 2-6 weeks to show results

When e-commerce brands notice declining open rates despite strong email content, the culprit is often Gmail's Promotions tab—not spam filters or technical authentication issues. GlockApps and Mailmend represent two fundamentally different solutions to this challenge. GlockApps operates as a diagnostic platform that tests where emails land across various providers, while Mailmend provides proprietary technology that actively changes where emails appear. This comparison reveals why Mailmend's execution-first approach delivers superior results for Klaviyo users who need revenue impact, not just deliverability reports.

Understanding Email Deliverability Challenges for E-commerce

E-commerce brands face a specific deliverability challenge that generic testing tools weren't built to solve. Gmail's algorithms automatically categorize promotional emails into the Promotions tab, where they receive significantly lower visibility and engagement compared to Primary inbox placement.

The Promotions tab problem impacts:

• Open rates dropping despite quality content

• Click-through rates declining without explanation

• Email revenue underperforming historical benchmarks

• Seasonal campaigns missing revenue targets

• Retention marketing failing to drive repeat purchases

The email deliverability tools market reached $1.2 billion in 2024, projected to grow to $2.41 billion by 2032 at a 9.1% CAGR. This growth reflects increasing recognition that inbox placement directly determines email marketing ROI.

Traditional deliverability solutions focus on sender reputation, authentication protocols, and spam filter avoidance. These approaches work for technical deliverability issues but fail to address Gmail's categorization algorithm—a separate system that sorts authenticated, reputable emails into lower-visibility folders based on promotional content signals.

For Klaviyo users specifically, this creates a gap: your emails might pass every deliverability test while still landing in the Promotions tab where subscribers rarely check. Mailmend addresses this exact problem.

Mailmend.io: A Deep Dive into Klaviyo-Exclusive Inbox Placement

Mailmend provides email deliverability software designed exclusively for e-commerce brands using Klaviyo. The platform's core offering is proprietary algorithmic technology delivered as a code snippet that integrates directly with Klaviyo templates.

How Mailmend's Algorithm Optimizes for Primary Inbox

Mailmend's technology operates through a three-step process:

1. Testing: Sends client emails to rotating test inboxes to determine current placement status

2. Analysis: Proprietary AI analyzes the "promotional threshold"—combined factors Gmail uses to categorize emails

3. Optimization: Generates account-specific custom code that counteracts promotional categorization signals

This approach differs fundamentally from diagnostic tools. While GlockApps tells you where emails land, Mailmend actively changes where they appear—without requiring modifications to email content, copy, or design.

Quick Setup and Immediate Revenue Impact

Mailmend's implementation process emphasizes speed:

• Setup time: Less than 5 minutes through drag-and-drop integration

• Results timeline: Measurable impact within 24 hours

• Technical requirements: No developer resources needed

• Content changes: Zero modifications to existing emails

The platform serves 500+ e-commerce businesses across personal care, apparel, home goods, food & beverage, and lifestyle categories. Documented case studies demonstrate consistent results across diverse product verticals.

GlockApps Overview: Comprehensive Email Testing & Monitoring

GlockApps has operated in the email deliverability space since 2009, building 15+ years of experience as a testing platform. The tool provides diagnostic capabilities for marketers seeking visibility into inbox placement across multiple email providers.

Key Features for Pre-Send Deliverability Assurance

GlockApps offers comprehensive testing capabilities:

• Inbox placement testing across 20+ ESPs

• DMARC analytics supporting up to 12M messages monthly

• Blacklist monitoring tracking 50+ blacklists including Spamhaus and SpamCop

• IP reputation tracking for up to 25 IPs

• Spam filter testing across 5+ major filters

• Authentication checks for SPF, DKIM, and DMARC

Post-Send Monitoring and Troubleshooting

The platform excels at identifying technical issues:

• Weekly and monthly DMARC digests

• Detailed spam filter analysis with actionable recommendations

• Performance reports across Gmail, Outlook, Yahoo, and other providers

• Blacklist alerts for proactive reputation management

However, GlockApps operates as a diagnostic tool. As noted in user reviews, the platform identifies problems without fixing them—users must remediate issues manually based on test results.

Mailmend's Unique Value: Bypassing the Promotions Tab Without Content Changes

The core differentiator between Mailmend and GlockApps lies in outcomes versus diagnostics. Mailmend actively solves the Promotions tab challenge; GlockApps identifies that the challenge exists.

The "Zero Changes" Advantage in Email Marketing

Traditional deliverability consulting requires comprehensive strategy overhauls:

• Rewriting email copy to reduce promotional language

• Redesigning templates to minimize promotional signals

• Adjusting sending frequency and timing

• Building new engagement segments

• Implementing complex technical configurations

Mailmend eliminates this overhead entirely. The platform's algorithmic approach works at the technical level rather than the content level, allowing brands to maintain proven promotional strategies while achieving Primary inbox placement.

This matters critically for seasonal campaigns. Brands cannot afford to A/B test new email strategies during Black Friday—they need existing, optimized content to reach subscribers immediately.

Client Success Stories and Revenue Guarantees

Mailmend's documented results demonstrate consistent performance across verticals:

• Dr. Squatch: Increased their email revenue by 112% escaping the promotions tab. In just 24 hours, Dr. Squatch ran a test to see how Mailmend was performing. Little did they know they were missing out on half the revenue they deserved. 42% increase in open rates and 67% increase in CTR.

• StickerYou: "Day 1 boost of 20% - 100% Increase by month 1." StickerYou was absolutely blown away by the results of Mailmend. After going through our videos and speaking to our team, they signed up. 64% increase in open rates and 43% increase in CTR.

• Ministry of Supply: "Results within a business day!" Although skeptical at first Ministry Of Supply was able to quickly get setup with Mailmend in a matter of business days and land in the inbox! 27% increase in open rates and 30% increase in CTR.

• Larsson & Jennings: Saved our black friday. Anna was suffering from low open rates & click rates after they had a data failure in their ESP. They also had massive promotions tab issues. We came in a fixed ALL of it. 82% increase in open rates and 51% increase in CTR.

• Amberjack: "It Actually Worked." Blake was looking for more incremental revenue after they noticed click rates take a dive. They ran some tests with Mailmend and instantly saw revenue shoot up. 54% increase in open rates and 51% increase in CTR.

• Clevr Blends: Made a big Difference. Clevr Blends was looking for an easy way to boost their email revenue after seeing low opens and clicks - so they came to Mailmend and saw amazing results. 21% increase in open rates and 63% increase in CTR.

Mailmend offers revenue satisfaction guarantees, aligning the platform's success with client outcomes. This performance-based approach demonstrates confidence in results that diagnostic-only tools cannot match.

Integration and Setup: Mailmend's 5-Minute Promise vs. GlockApps' Configuration

Implementation complexity determines how quickly brands see results and how much internal resource they require.

Mailmend's Plug-and-Play Approach for Klaviyo Users

Mailmend's native Klaviyo integration provides unique advantages:

• Drag-and-drop code insertion directly in Klaviyo's template editor

• No developer resources required for implementation

• Works with existing flows including abandoned cart, post-purchase, and browse abandonment

• Supports campaign emails for promotional sends and newsletters

• Enables native A/B testing within Klaviyo's analytics dashboard

GlockApps' Flexibility Across ESPs

GlockApps operates through seed list testing, providing broader ESP compatibility:

• Works with any email platform via seed email addresses

• Requires copying test addresses into campaign recipient lists

• Provides results through external dashboard, not native ESP analytics

• 10-15 minutes typical setup time per test

• No direct integration with Klaviyo's A/B testing infrastructure

For agencies managing multiple ESPs, GlockApps' universal compatibility offers value. For Klaviyo-focused e-commerce brands, Mailmend's native integration delivers faster implementation and easier performance measurement.

Performance Measurement & ROI: A/B Testing with Mailmend vs. GlockApps Reporting

Measuring deliverability impact determines whether investments generate positive ROI.

Measuring Direct Lift with Mailmend's Klaviyo A/B Testing

Mailmend enables performance validation within your existing analytics:

• Split test emails with and without Mailmend code to measure exact lift

• Track open rate differences between Primary and Promotions placement

• Measure CTR variance across test groups

• Monitor revenue attribution to each variant through Klaviyo's native reporting

• Calculate email marketing ROI improvement with direct comparison data

This approach provides immediate performance validation without requiring external tools or manual data compilation.

Comprehensive Deliverability Metrics from GlockApps

GlockApps offers detailed diagnostic reporting:

• Inbox placement rates across 20+ email providers

• Spam folder delivery percentages

• Authentication status (SPF, DKIM, DMARC pass rates)

• Blacklist status across 50+ databases

• Content analysis with spam score predictions

However, these diagnostics don't translate directly to revenue impact. A brand might achieve 95% inbox placement on GlockApps tests while still seeing emails land in Gmail's Promotions tab—a placement that passes deliverability checks but reduces engagement.

Target Audience and Business Model: Mailmend's E-commerce Focus vs. GlockApps' Broad Appeal

The tools serve different market segments with different needs.

Who Benefits Most from Mailmend's Specialized Approach?

Mailmend targets specific use cases:

• Seven-to-eight-figure e-commerce brands experiencing declining email performance

• Klaviyo users seeking native platform integration

• DTC brands across consumer product categories

• Retention marketers prioritizing email revenue over vanity metrics

• Time-sensitive campaigns including Black Friday, product launches, and seasonal sales

The platform's partnership model with dedicated 1-to-1 representatives ensures hands-on support rather than self-service troubleshooting. Brands interested in exploring this approach can contact Mailmend to discuss their specific deliverability challenges.

GlockApps' Versatility for Various Email Marketing Needs

GlockApps serves broader use cases:

• Agencies managing clients across multiple ESPs

• B2B companies focused on cold outreach deliverability

• Technical teams requiring detailed authentication diagnostics

• Enterprise senders needing DMARC compliance monitoring

• Marketers wanting pre-send spam filter testing

However, GlockApps shows limited B2B testing accuracy with only 11 professional inbox accounts versus 12+ personal accounts in their testing network.

Pricing and Support: Performance-Based vs. Subscription Models

Pricing structures reflect each platform's value proposition.

Mailmend's Partnership Approach and Revenue Guarantees

Mailmend operates on custom pricing requiring a demo consultation:

• Partnership-based model aligning success with client outcomes

• Revenue satisfaction guarantee ensuring measurable impact

• White-glove onboarding included in partnership

• Dedicated representative for ongoing optimization

• Unlimited usage without per-test or per-email fees

The platform emphasizes ROI over cost: for brands generating $100,000 annually in email revenue, a 100%+ revenue increase generates over $100,000 in additional revenue—far exceeding platform investment. Agencies interested in offering Mailmend to clients can explore partnership opportunities.

GlockApps' Transparent Pricing and Community Resources

GlockApps offers tiered subscription pricing:

• Free tier: 2 test credits, 10K DMARC messages monthly

• Essential: $59/month annual with 360 test credits

• Growth: $99/month annual with 1,080 credits

• Enterprise: $129/month annual with 1,800 credits

However, users report significant concerns about pricing volatility:

• Monthly credit expiration creating "use it or lose it" pressure

• Additional spam tests costing $3-5 per test beyond subscription

• Complex multi-tier pricing across Bundle, DMARC-only, and Credit Pack options

Why Mailmend Delivers Superior Value for Klaviyo E-commerce Brands

For e-commerce brands using Klaviyo, the choice between Mailmend and GlockApps comes down to outcomes versus diagnostics.

Mailmend advantages for Klaviyo users:

• Solves the actual problem: Algorithmic technology moves emails from Promotions to Primary—GlockApps only identifies placement without changing it

• Immediate revenue impact: 24-hour results versus weeks of manual optimization

• Native Klaviyo integration: <5 minute setup with drag-and-drop implementation

• Zero content changes: Maintains proven promotional strategies without copywriting revamps

• Revenue guarantee: Performance-based model ensures measurable outcomes

• E-commerce specialization: Built specifically for DTC brands, not generic email senders

GlockApps serves valid use cases—comprehensive ESP testing, DMARC compliance, blacklist monitoring—but these capabilities address different challenges than Gmail Promotions tab placement.

For Series A+ e-commerce brands seeking revenue acceleration without deliverability diagnostics they must implement themselves, Mailmend represents the superior approach to email marketing optimization.

Frequently Asked Questions

How does Mailmend.io move emails to the Primary inbox without changing content?

Mailmend uses proprietary AI to analyze Gmail's "promotional threshold"—the combined factors the algorithm uses to categorize emails. The platform generates account-specific custom code that counteracts promotional categorization signals at the technical level rather than the content level. This approach allows brands to maintain existing email copy, design, and strategy while achieving Primary inbox placement. The technology works through code embedded in Klaviyo templates, requiring no modifications to actual email content.

Is Mailmend.io only compatible with Klaviyo?

Yes, Mailmend integrates exclusively with Klaviyo, providing a native drag-and-drop integration for inbox placement optimization. This specialization enables features that generic tools cannot offer—including direct A/B testing within Klaviyo's analytics dashboard and support for automated flows. Brands using other ESPs like Mailchimp or Omnisend would need alternative solutions, though GlockApps can provide diagnostic testing for those platforms without actively improving placement.

What kind of results can I expect when using Mailmend.io for my Klaviyo emails?

Documented case studies show consistent results across e-commerce verticals: Dr. Squatch achieved 112% email revenue increase with 42% open rate and 67% CTR increases, StickerYou saw initial 20% improvement growing to 100% revenue increase by month one with 64% open rate and 43% CTR increases, and Ministry of Supply recorded 27% open rate and 30% CTR increases within one business day. Mailmend offers revenue satisfaction guarantees, ensuring measurable impact from the partnership.

Can smaller e-commerce brands benefit from Mailmend.io, or is it only for large businesses?

Mailmend targets seven-to-eight-figure e-commerce brands that have achieved sufficient email volume to benefit from improved inbox placement. The platform's custom pricing model through demo consultation allows evaluation based on specific business size and needs. For brands generating meaningful email revenue, the ROI from up to 100%+ revenue increases typically exceeds platform investment significantly, making the solution viable for growth-stage companies beyond enterprise-only pricing.

What data can I use from Klaviyo to measure Mailmend's performance?

Mailmend's native Klaviyo integration enables direct performance measurement through A/B testing. Brands can split audiences to compare emails with and without Mailmend code, tracking open rate differences, click-through rate variance, and revenue attribution within Klaviyo's existing analytics dashboard. This approach provides immediate performance validation using familiar reporting tools rather than requiring external data compilation or manual analysis.