By David,
Let's start with the respect CodeTwo has earned. CodeTwo Email Signatures 365 is one of the most established names in Microsoft 365 signature management - widely deployed, consistently well reviewed, and built by a company that has been doing Exchange tooling for a long time. If you ask a Microsoft 365 admin community to name a signature product, CodeTwo is one of the first answers you'll hear.
So this isn't a hit piece. It's an architecture comparison - because CodeTwo and Atlas Ink answer the same question ("how do we get every employee's signature on brand and keep it there?") in fundamentally different places, and the place you pick decides almost everything downstream.
The short version: CodeTwo's flagship mode stamps the signature onto mail in transit, which guarantees coverage on every message from every device - and puts a third-party cloud service into your mail flow to do it. Atlas Ink writes the finished signature into the mailbox itself, so it becomes the signature Outlook composes with: no transport rules unless you opt in, no add-in, and no mail ever routed through Atlas. If you don't want anything new in your mail path, Atlas Ink is built on exactly that refusal - at $1 per active user, per month, always.
Two architectures, one problem
CodeTwo's primary mode is server-side. Exchange Online connectors route outbound mail through CodeTwo's Azure-hosted service, which adds the signature and hands the message back for delivery. That's what "signatures on every device" means mechanically: the phone's native mail app doesn't need to know a signature exists, because the signature is applied after the message leaves the phone. CodeTwo also offers a client-side mode - an Outlook add-in that inserts the signature while the user composes - and the two can be combined.
By default, Atlas Ink doesn't stamp anything. It resolves which template applies to each user, fills in the tokens from their Entra ID profile - name, title, department, phone - and pushes the finished signature into the mailbox as the user's own Outlook signature. Mail leaves your tenant exactly the way Exchange Online sends it. There is no connector, no re-routing, and no service between your users and their recipients.
For clients that can't read the mailbox signature - classic desktop Outlook, Apple Mail, and other non-Outlook apps - Atlas Ink also offers an opt-in server-side stamping mode. An admin turns it on explicitly; it creates one mail-flow rule in your own Exchange Online that appends the signature on every send, and it isn't available in GCC or GCC High. The difference from CodeTwo's server-side mode is where the stamping happens: inside Exchange, with no connector and no vendor cloud, so mail still never routes through Atlas.
Neither approach is wrong. They're different answers to the question "where should the signature live?" - and each answer has consequences worth seeing clearly before you buy.
What follows from the architecture
The mail path. Server-side stamping means a third-party service processes your outbound mail. CodeTwo treats that responsibility seriously and says so publicly - but your compliance and mail-privacy reviews now have one more system in scope, and that's true no matter how trustworthy the vendor is. Atlas Ink's provisioning runs through your admin-consented Atlas app registration, with an Exchange role scoped to signature settings; no message content ever reaches Atlas, which keeps it out of scope for mail-path reviews entirely.
What the sender sees. With in-transit stamping alone, the sender composes a message with no signature and the recipient gets one - the final email doesn't match what the sender saw (CodeTwo's add-in mode exists partly to close that gap). With Atlas Ink, the pushed signature is the Outlook compose signature, so what the user sees while typing is what the recipient receives.
Who wins an edit. A transport rule always wins: whatever the user types, the stamped signature is what goes out. Atlas Ink enforces too, but at the mailbox and with a switch - by default a daily reconcile re-applies the assigned signature if a user edits or clears it, and an admin can switch individual users to unmanaged to let them set their own. So the same product serves the compliance team that wants the signature locked and the team that wants to hand a few people the pen: you choose per user, not per mail rule.
The side-by-side
| Atlas Ink | CodeTwo Email Signatures 365 | |
|---|---|---|
| Where the signature is applied | Pushed into the mailbox; becomes the Outlook compose signature | Stamped in transit (server-side) and/or inserted by an Outlook add-in |
| Mail routed through the vendor | Never | Yes, in server-side mode |
| Anything to install or deploy | Nothing - no agent, no add-in | Add-in for client-side mode; connectors for server-side |
| Personalization data | Entra ID merge tokens | Microsoft 365 / Entra ID attributes |
| Targeting | Tenant → group → user; most specific scope wins | Rules engine (senders, recipients, keywords, and more) |
| User edits their signature | Re-applied daily by default; switch a user to unmanaged to let them keep their own | Server-side signature is applied regardless |
| Pricing model | $1/user/mo, metered | Per-user subscription, tiered by seat count |
| Billing | Prepaid units, billed via Stripe (no seat commitment) | Separate vendor subscription |
Where Atlas Ink shines
Atlas Ink is for the organization whose signature problem is hygiene, not marketing: several hundred mailboxes, a dozen home-grown signature variants, and nobody sure which one is current. It fixes that with three moves - author a template once, assign it by tenant, group, or user, and push it into every mailbox, hydrated per person from Entra ID. When someone changes role, the next push picks up their new title. Nobody retypes anything, and there's per-user status - applied, pending, or failed - so you know it landed.
And the commercial model matches the scope. Atlas Ink is $1 per active user, per month, always - a user is billable only in a calendar month where a managed signature is actually applied to their mailbox. No seats to pre-buy, no annual commitment, and units are billed as a small prepaid charge via Stripe. Remove a user's managed signature and they stop counting. It's an add-on available on every Atlas AVD plan, including the free Community tier.
Atlas Ink is administered from the Atlas AVD console, so if you already run Atlas it slots straight in - and if you don't, a free Community subscription gets you the console.
How to think about the decision
Ask three questions:
- Should your people see the signature they're sending? With in-transit stamping they compose blind; with Atlas Ink, what they see while typing is exactly what the recipient receives.
- Is a third-party service in the outbound mail path acceptable to your compliance posture? If the answer is no, mailbox provisioning is the only architecture that satisfies it - and that's the architecture Atlas Ink is.
- Do you want to pay for licensed seats or for applied signatures? A per-user subscription bills everyone you license, all year. A metered dollar bills the users who actually carry a managed signature that month, and stops when you stop.
The verdict: choose by architecture, not by feature-list length. If what you need is every mailbox on brand, filled from Entra ID, with your mail path untouched and a bill that only counts active signatures - that's exactly the product Atlas Ink is.
Feature and pricing details for CodeTwo Email Signatures 365 are drawn from CodeTwo's public materials as of August 2026 and summarized in good faith; CodeTwo publishes per-user pricing on its website. Confirm current features and pricing with CodeTwo directly.