Synthetic warm-up gets a blocklist, agentic email assembly ships, and a platform starts billing on clicks
Four developments to inspect this week: a blocklist that names synthetic domain warming, agentic email assembly arriving for enterprise brands, a platform moving to click-based email pricing, and Microsoft cutting Apple Mail on macOS off from Microsoft 365 mailboxes.
Coverage window: October 2, 2026 at 10:16 through October 7, 2026 at 10:15 (UTC+02:00). The window runs five days, because the previous issue went out on Friday and the schedule's next slot is Wednesday. It holds four developments. The first is the one with the shortest deadline, because it can land on your own sending domain. The second is a week of tool releases that move email production toward AI agents. The third is a pricing change that puts a bill on the click. The fourth is a Microsoft retirement date that reaches a cohort of your readers.
Synthetic warming has its own blocklist now
What changed
All About Email, the practitioner newsletter written by Simon Harper, gave its October 5 issue to the two things sold under the name email warm-up, and to a blocklist that separates them. 1 Validity, the email data company that owns Litmus, launched that blocklist on September 3, 2026 under the name Heatwave, aimed at synthetic warming and the cold-email infrastructure around it, and said at launch that it had already listed more than one million domains showing artificial-warming patterns. 12
The distinction the issue draws decides what a sender is buying. A real warm-up raises sending volume gradually into people who asked to hear from the brand, watches what happens, and adjusts the pace; Resend's own warm-up guidance describes that process. 3 Synthetic warming runs controlled mailboxes that exchange messages with one another and manufacture the opens, clicks and replies that make a sender look trusted. 1 Both get sold as warm-up, and only one of them involves a real subscriber reading a message.
The anti-abuse community reached that conclusion before the blocklist did. The Messaging Malware Mobile Anti-Abuse Working Group published a position on cold email in November 2025 that condemns the artificial simulation of subscriber engagement and the methods used to evade filtering. 4 Al Iverson, who writes Spam Resource, said on September 9 that he regularly hears from senders who come to him after using a warming or outreach service, arriving with inbox-placement problems and a domain reputation worse than where they started. 5 Matt Vernhout's EmailKarma piece places Heatwave in that same line of work. 6
Heatwave lists domains and leaves IP addresses alone, and its entries carry a classification: a synthetic-warming history reads differently from later active cold outreach. 1 A confirmed synthetic-warming observation keeps its place after the activity stops, and the active-outreach status can change on its own, according to Validity's listing policy; a classification the company got wrong can be reviewed and removed. 7 Each mailbox provider decides for itself how much weight a listing carries. 6
Why it matters
Validity warns that warming activity can run under a brand's name without the brand knowing, and that its lookup surfaces related domains. 1 An agency, an outbound sales team, or a subcontractor working for an outbound vendor can be warming domains your organisation owns, and the classification attaches to the domain either way.
Warming is bought to protect a domain, and the version Validity is listing can leave one in worse standing than it started, which is the pattern Iverson describes. 5 The cost of finding out later is a sending problem during the quarter when sending matters most.
Checks before acting
- Ask every team and supplier for the domains and email accounts they run on your behalf: who owns each one, who has access, and what it sends. 1
- Run those domains through the Heatwave lookup and read the classification on any hit before deciding what to do about it. 8
- Where a listing looks wrong, take it to Validity's review process. 7
- Put one question to any warm-up vendor you are paying: which of the two processes does it run, who receives the messages, and where does the engagement come from? 1
Email production moves up the list of jobs handed to an agent
What changed
Stensul, which sells email production software to large brands, announced four capabilities in its October release on October 6: agentic email assembly through the Model Context Protocol, the interface AI assistants now use to work inside other companies' software; brand voice guardrails; Figma-to-email production at scale; and AI translation. 910 Manlio Carrelli, the company's chief executive, said the goal is campaigns "that reach more audiences and create more opportunities to convert". 9
Small businesses got their version the same week. Follow Inc opened the beta of followOS-email on October 2, the first feature of what it calls an autonomous AI advertising system for small and medium-sized firms, and is offering access by invitation. 11 A user describes the business and how it communicates, pulls in the list, and the product supplies automated customer flows, a consistent brand voice, product-aware content and analytics. 11 Dean K. Ladell, its chief executive, says the aim is email that "looks like the business hired a studio", and that an AI search product follows in the fourth quarter. 11
The customers on the other end of those campaigns have their own view of how far an agent should go. Ping Identity surveyed 11,000 consumers worldwide and found 5% comfortable with an AI agent taking actions they have already approved, and 3% comfortable with routine transactions that get no final approval. 9 Comfort rises to 27% for low-stakes support and 29% for recommendations, and 42% would let an agent spend up to $100 and no more, while 22% would permit no financial transaction of any size. 9 71% worry that an agent acting for them could misrepresent their personality or their values, and 47% say checking an agent's work is a bigger hassle than the agent making a mistake. 9
Why it matters
The releases this month put campaign assembly in the agent's hands alongside campaign copy, and the guardrails being sold with it are brand voice rules and human approval. 910 The volume of variants is the constraint the vendors are aiming at, so the review time a team spends per campaign is the line that moves.
The survey gives a marketing leader the boundary in the customer's own terms. Spend authority and voice are the two things consumers hold back, which is exactly the pair a generative campaign tool reaches for first.
Checks before acting
- Write down which changes an agent may ship without a human sign-off, and set the brand voice rules before enabling generated variants. 10
- Treat the platform claims in an invitation-only beta as unmeasured until your own list has run through it; the announcements carry vendor figures and no published methodology. 11
- Check any agent that touches customer data against the limits consumers named: what it may spend, what it may say in their name, and who approves before it acts. 9
A platform puts a price on the click instead of the send
What changed
Treasure AI used its Agentic World conference in Miami on October 6 to announce two things. The first is Personalization Studio, a workspace for building and running real-time website personalisation, available now to its customers. 12 The second is a pricing change: the company will charge for email according to what customers do with a message, such as clicking, in place of how many messages a brand sends. 12 Rates, tiers and a start date went undisclosed. 12
Rafa Flores, the company's chief product and growth officer, told CMSWire that pricing should follow the value a platform produces, and that he expects Braze and Klaviyo to face the same question. 12 Pay-per-click is ordinary in advertising, he said, and an email service provider had not billed that way before. 12 Gartner expects at least 40% of enterprise SaaS spend to move toward usage-, agent- or outcome-based pricing by 2030, as cited in Deloitte's 2026 predictions. 13
The unit that pricing rests on is broader than the word suggests. Mailgun's October 5 post on open tracking works through what a recorded event contains: an image request that deliverability specialist Laura Atkins calls a "pixel load" can come from a mail client displaying the message, an image proxy fetching on the recipient's behalf, a privacy service retrieving images automatically, a security system inspecting the message, a cache refreshing it, or another automated process sitting somewhere between the sender and the screen. 14
Why it matters
On a click-based bill the definition of a click moves out of your reporting settings and into the contract. 12 Two vendors can bill the same campaign differently if one filters automated activity and the other counts it. 14
Flores named Braze and Klaviyo as the vendors he expects under pressure, which means the model belongs on the agenda at your next platform renewal. 12
Checks before acting
- Ask any vendor proposing engagement-based pricing for its click definition in writing: which events count, how automated activity is handled, and what a quiet month costs you. 1214
- Price your last quarter both ways, on sends and on clicks, so the comparison uses your own numbers. 12
- Check what your analytics already separates before you accept a bill built on the raw number. 14
Apple Mail on a Mac is losing its Microsoft 365 mailboxes
What changed
Microsoft began disabling Exchange Web Services in Exchange Online on October 1, 2026, switching it off by default as part of a phased rollout ahead of shutting it down completely in April 2027. 15 EWS is the older protocol that third-party applications and Apple's desktop apps have used to reach Exchange mailboxes; Microsoft announced its retirement in 2018 and set the October 2026 disablement date in 2023. 15
Spam Resource's October 5 post points at who notices first: Apple's native macOS applications, among them Mail, Calendar, Contacts, Notes and Reminders, still reach Exchange Online over EWS, so a person using a Microsoft 365 work or school account in Apple Mail on a Mac can find the mailbox stops syncing. 16
The scope is narrower than the headline. The change covers cloud-hosted Microsoft 365 accounts on macOS; on-premises Exchange servers are untouched, and iPhones and iPads keep working because they connect through Exchange ActiveSync instead. 16 Apple is moving its desktop apps to Microsoft Graph and has given no release date for the change. 16
Until then an administrator can re-enable EWS for approved applications inside the tenant, or direct Mac users to Outlook or webmail. 16 Microsoft publishes EWS usage reports and an analyser tool for finding the internal and vendor applications that still depend on the protocol. 15
Why it matters
Part of any list reads work mail in Apple Mail on a Mac, and those readers move to another client or another device while the mailbox is dark, so their engagement arrives from somewhere else for as long as the transition lasts. 16
For an email or CRM team running Microsoft 365, the fix sits in a tenant setting or a client switch, which puts the decision in IT's hands. The April 2027 endgame is the date to plan against, and the months before it are when the applications still speaking EWS get found. 15
Checks before acting
- Ask IT whether your organisation's Microsoft 365 tenant still allows EWS for Apple applications, and who decided that. 15
- Work through Microsoft's EWS usage reports to list the internal systems and vendor tools still depending on the protocol, then set a migration order. 15
- Tell the Mac users on your own team which client to use, and put that switch on the calendar before their mailboxes go dark. 16
Next audit
Two dates come out of this issue. Before the holiday sending calendar locks, collect the domains your suppliers send from and run them through the Heatwave lookup; a listing found in October is a conversation, and one found in November is a week of sending nobody can explain. The Microsoft 365 change has a longer runway: administrators on macOS have until April 2027 and should spend the months before it finding every application that still speaks EWS. The question to carry into the next platform renewal is what your bill will be measured in, now that one vendor has said clicks.
References
- 1Is your email warm-up building trust, or faking it?
newsletter.allabout.email
- 2Validity Launches Heatwave Blocklist
validity.com
- 3Warming up
resend.com
- 4M3AAWG position on cold email
m3aawg.org
- 5New from Validity: The Heatwave Domain Blocklist
spamresource.com
- 6New blocklist flags synthetic email warm-ups
emailkarma.net
- 7Heatwave listing policy
lookup.validity.tools
- 8Heatwave lookup
lookup.validity.tools
- 9
- 10October release: More relevant email
stensul.com
- 11
- 12
- 13
- 14
- 15Deprecation of Exchange Web Services in Exchange Online
learn.microsoft.com
- 16Mac Users Face Microsoft 365 Sync Issues as EWS Phased Out
spamresource.com
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