164: Ruari Baker: The 3 most important things you can do for email deliverability: Multi-subdomains, email validation 3.0 and good ol’ postmaster

What’s up everyone, today we have the pleasure of sitting down with Ruari Baker, Co-Founder and CEO of Allegrow.

Summary: Your fancy AI personalization messaging strategy doesn’t mean anything if you don’t also have a strategy for email deliverability. Ruari busts long-standing myths about HTML vs plain text, why open rates died with Apple's 2021 privacy changes, and why the spam complaints visible in your marketing platform represent a fraction of reality. You'll walk away with 3 deliverability tactics that will help you reach the inbox and stay there: implement multi-subdomains to isolate high-risk traffic, adopt contact risk scoring that transcends basic validation and start using Google Postmaster to see your actual reputation metrics. Escape the promo tab without sacrificing design, resurrect damaged domains, and find out why traditional seed testing is worthless. If you depend on email, this might be the best 40 minutes you’ll spend this month.

About Ruari

• Ruari started entrepreneurship early (at 18 years old) and joined a startup accelerator where he received mentorship from top tech founders in the UK as well as his first investment
• He co-founded Direct Software, a GDPR-first marketing automation solution where he gained a deep understanding of email deliverability
• Today, Ruari is Co-Founder and CEO of Allegrow, an email deliverability platform to help emails reach the primary inbox, not the spam folder

Plain Text Emails Will Always Outperform HTML Emails When it Comes to Inbox Placement

The HTML vs text email question hangs over every marketer's campaign planning session like a dark cloud. Ruari slices through this persistent debate with razor-sharp clarity. Context dictates winners here, not blanket rules. For outbound sales, plain text creates an authenticity that HTML instantly kills. Think about it—you craft personal emails without fancy formatting. The second your recipient spots that polished design, their brain categorizes your message as "marketing material," and your personalization efforts crumble.

> “You can't just simply say 'always plain text, that's better.' The reality is there are still good business reasons for using Rich HTML, and that's why it is such a popular way to send emails from a marketing perspective.”

Email providers have learned to associate complex formatting with promotional content that users often ignore. Your deliverability suffers accordingly. Yet HTML emails persist for good reason:

Large subscriber lists benefit from HTML's clickthrough tracking capabilities
E-commerce companies generate higher engagement when customers see products directly
Visual brands communicate their identity more effectively through designed templates
Data-heavy messages become more scannable with proper formatting and hierarchy

The winning strategy lives somewhere in the messy middle. "If you're using HTML for legitimate marketing emails to an opted-in list, implement these practices to maintain deliverability," Ruari advises. Clean your entire list monthly—remove invalid contacts, keep bounce rates low, and eliminate potential spam trap subscriptions. This simple 30-day hygiene ritual dramatically improves your sender reputation with both ESPs and inbox systems.

HTML devotees should strategically incorporate plain text messages at key points in the subscriber journey. These unadorned communications slip past promotion folder algorithms, landing you in the primary inbox. This placement success creates a virtuous cycle, improving future message placement—even for your HTML campaigns. You must also implement a sunset policy for engagement maintenance. When subscribers show zero activity over your predetermined period, place them into a final-attempt workflow. No response? Remove them proactively. This keeps your engagement metrics healthy, the exact data points email providers scrutinize when judging your sending quality.

"I once worked with an e-commerce client who switched half their abandoned cart emails to plain text," Ruari shares. "Their revenue per email jumped 22% because more messages reached the primary inbox." The results speak volumes about matching format to objective rather than defaulting to what looks prettiest in your marketing dashboard.

Key takeaway: Match email format to specific objectives. Use plain text for sales outreach and relationship-building. Deploy HTML strategically for e-commerce and visual campaigns. Maintain ruthless list hygiene by removing invalid contacts monthly, sending occasional plain text messages regardless of your primary format, and cutting unengaged subscribers after final reactivation attempts. Your deliverability—and ultimately your results—depend on this discipline.

Create a Sunset Policy Based on Your Specific Industry Engagement Patterns

Your email list contains a ticking time bomb of disengaged contacts that silently damage your sender reputation with every campaign. When asked about the right timeframe for removing inactive subscribers, Ruari offers a refreshingly nuanced take that shatters the "six-month rule" most marketers blindly follow. The optimal sunset policy timing depends entirely on your industry and baseline engagement metrics. Smart marketers look to identify and remove the bottom quartile or decile of subscribers based on engagement patterns specific to their audience.

High-engagement industries demand different standards than low-engagement sectors. Imagine running email marketing for a compliance software company—a field few people find "sexy." Your engagement metrics naturally run lower than consumer brands, but those rare engagement spikes matter tremendously. When someone suddenly engages with your SOC 2 audit content after months of silence, that signals a critical buying window. Cutting them off after six months of inactivity would sacrifice valuable revenue opportunities unique to your industry cycle.

You must establish internal benchmarks that reflect your specific business reality. Study your engagement patterns over 12-18 months. Look for natural dropoff points. Analyze which inactive subscribers eventually reactivate and what triggers that behavior. Create segments based on these findings, then craft sunset workflows that reflect the actual customer journey in your space. For some businesses, 90 days makes sense. For others, 12 months barely captures their sales cycle.

> “At least having some sunset policy in place would already put you leaps and bounds ahead of the majority of your peers.”

The mere existence of a sunset policy puts you "leaps and bounds ahead of the majority of your peers," Ruari points out. Most marketers obsessively protect their list size, treating subscriber counts as a vanity metric rather than focusing on engagement quality. They hoard inactive emails like digital dragons, destroying deliverability in the process. Your sunset policy doesn't need to be perfect—it simply needs to exist and run consistently. Start by removing obvious dead weight: bounced addresses, spam complaints, and truly inactive accounts. Then refine your approach as you gather more data about your specific audience patterns.

Key takeaway: Create a sunset policy based on your specific industry engagement patterns rather than arbitrary timeframes. Identify your bottom-performing subscriber segment (by quartile or decile) and implement an automated workflow to either re-engage or remove them. Even an imperfect sunset policy executed consistently will dramatically improve your deliverability metrics and campaign effectiveness compared to never removing inactive subscribers.

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