Two of the five AI email tools this guide originally recommended had already been acquired and absorbed into other companies before or around the time the article was published in December 2018. That’s not really a criticism of the original guide, it’s a preview of how fast this specific corner of martech moves, and it hasn’t slowed down.

63% of marketers now use AI tools in email marketing, according to Knak’s 2026 research, and 95% of marketers who use generative AI specifically for email content creation say it’s effective. That’s a genuinely different landscape than 2018, when “AI in email marketing” mostly meant a handful of specialized send-time and subject-line tools bolted onto a traditional email platform. Generative AI now writes entire campaigns, not just subject lines, and the tool landscape underneath it has turned over almost completely.

What the original guide’s tool list actually looked like by 2026

Boomtrain Acquired before this article’s publish date

Siftrock Acquired the same year this was published

Phrasee Rebranded, still operating

Seventh Sense and Optimail

What’s genuinely new: generative AI writes the whole email now

The original guide’s core claim, that AI-personalized subject lines outperform human-written ones, still holds, and it’s now backed by considerably more current data. AI-generated subject lines increase open rates by up to 22%, with typical improvements in the 5% to 10% range, according to 2026 research, a more measured and better-sourced figure than the vague “95% more effective” claim the original guide cited from Phrasee’s own marketing material.

What genuinely didn’t exist in 2018 is generative AI writing the full body of an email, not just optimizing a subject line or send time. 54% of marketers now actively use AI for crafting personalized newsletters, up from 36% who merely planned to in the prior year, according to a 2026 Mailchimp and MIT Technology Review survey of 7,300 marketing professionals, and early adopters report a 43% improvement in click-to-open rates alongside a 29% reduction in unsubscribe rates compared to brands still using manually segmented, static templates.

Personalization and revenue: the numbers have gotten more specific

The original guide’s claim that over 50% of consumers switch brands over poor personalization remains directionally accurate and continues to be cited. What’s newly measurable is the revenue impact: AI-driven email personalization delivers a 41% revenue increase compared to non-personalized, batch-and-blast sends, according to 2026 research, and segmented campaigns generate 760% more revenue than non-segmented broadcasts. Neither figure existed in this form in 2018, when personalization was still mostly limited to inserting a first name into a subject line.

The practical takeaway for 2026

The original guide’s underlying argument, that AI removes tedious manual work from email marketing and lets marketers focus on strategy, remains completely correct, it’s just executing on a much bigger scope than it was in 2018. Whatever platform you use, most major email service providers now build AI subject-line, send-time, and content generation directly into their core product, reducing the need to stitch together five separate specialized tools the way this guide originally recommended. For a broader look at how AI fits into your overall marketing stack, it’s worth reviewing alongside artificial intelligence in marketing and conversion optimization tools more generally, since email increasingly functions as one piece of a connected, AI-assisted funnel rather than a standalone channel.

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