Signatures for Replies, Internal Emails, Aliases and Shared Mailboxes: An IT Admin Guide (2026)

TL;DR: One signature for every situation is too heavy for replies and too external for colleagues. Scribe gives each signature a Primary design plus optional On-Reply and Internal variants, applied by the Outlook add-in and by server-side routing in Microsoft 365 and Google Workspace, but not by the client-side Gmail install. Server-side, a subject starting with Re:, Fw: or Fwd: means reply, and all recipients on the sender's domain means internal. Aliases can each have their own signature at no extra cost, chosen by the From address; Microsoft 365 needs sending from aliases enabled and Gmail needs each alias added as "Send mail as". Microsoft 365 shared mailboxes can be imported from Entra ID and given their own signature; on Google Workspace, a shared address is added as an alias for each person who sends from it. A seat is a person whose primary email has a signature; aliases are free.

Last reviewed: October 2026. Covers Scribe signature variants, email aliases (Exchange Online proxy addresses and Google Workspace alternate addresses) and Microsoft 365 shared mailboxes.

This guide covers the four situations where "one signature per person" stops working: replies and forwards, internal email, sending from an alias such as sales@ or a second domain, and team mailboxes such as support@. It is written for admins setting the rules, so it explains what each mail platform does natively, what the signature tool decides, which combinations are documented, and which ones you should test before promising them to anyone. Licensing comes at the end.

Why do new emails, replies and internal emails need different signatures?

A full external signature (photo, title, phone numbers, social icons, banner, disclaimer) earns its space on the first message to a prospect. On the fifth reply in a thread it is clutter, and in a message to a colleague the banner is advertising to your own staff. Three designs cover most companies:

Context	Purpose	Typical content
Primary (new email)	Introduce the sender and the brand	Name, title, company, phones, logo, social icons, banner, legal text
On-reply (replies and forwards)	Keep the thread readable	Name, title, one phone number, legal text; no banner or photo
Internal	Identify the sender to colleagues	Name, title, department, internal extension

This is close to Scribe's own suggested setup: a full primary signature with the campaign banner, a shorter on-reply variant without the banner, and a minimal internal variant with name and title (Signature variants). One adjustment for regulated industries: keep the legal disclaimer in the reply variant. Replies go to external recipients too, and a confidentiality notice or regulatory statement is usually required on those messages as well. The email disclaimers guide covers wording.

Which deployment methods apply reply and internal variants?

Variants depend on how the signature is installed. Scribe documents three cases (Signature variants):

Deployment	Variants applied?	How the context is decided
Microsoft 365 add-in (Outlook)	Yes	Outlook has three signature slots, Primary, Reply and Internal, which Scribe fills (Teammate profile)
Server-side, Microsoft 365 or Google Workspace	Yes	Per message, as Scribe processes it (rules below)
Client-side Gmail (Google Workspace app)	No	Gmail settings hold a single signature per address, with no variant per context

For server-side routing, Scribe states the rules it applies to each message (Microsoft 365 server side, Google Workspace server side):

• On-reply when the subject starts with a reply or forward prefix such as Re:, Fw: or Fwd:, including localized equivalents.
• Internal when every recipient is on the same domain as the sender.
• Primary in every other case.

Read those rules carefully, because they have edge cases worth knowing:

• "Internal" is domain-based. Mail from acme.com to a colleague at a sister domain such as acme.co.uk gets the primary signature.
• One external recipient on the line makes the whole message external.
• A reply whose subject someone retyped without the prefix is treated as a new email.

If Google Workspace is your platform and replies matter, that is a reason to add server-side routing; the Google Workspace guide covers setup. Variants are a paid feature, not on the free plan (pricing).

How do you set up reply and internal variants?

1. Open the signature and go to the Variants tab.
2. Set Activate On-Reply signature and/or Activate Internal signature to Yes. With No, that context uses the primary signature.
3. From the ⋯ menu on a variant card, choose Edit Variant to design it independently, or Reset to Primary Signature to start over from the primary design.
4. Decide per variant whether the marketing campaign appears, with its own Activate Marketing Campaign toggle.
5. Check all three contexts in Preview Signatures, which has Primary, Reply and Internal tabs.

Steps are from Signature variants and Preview signatures. Variants are managed per signature, so a company with ten department signatures has up to thirty designs to keep aligned. Two ways to keep that under control: start each variant from Reset to Primary Signature and remove blocks rather than designing from scratch, and script it. The API can list a signature's variants, upsert one, publish it, or reset it to the primary (API reference), and the signature.published webhook reports which kind was published: primary, reply_variant or internal_variant (Webhook events).

How do signatures work with aliases and send-as addresses?

An alias is a second address on the same mailbox: jane@company.com also receiving sales@company.com or jane@company.de. Two separate things have to be true for an alias to carry its own signature: the mail platform must let the person send as that alias, and the signature tool must know which signature belongs to it.

On the Scribe side

• Each teammate has one signature for their primary email and can have unlimited alias signatures. Scribe charges per user, not per signature, so aliases cost nothing extra (Aliases).
• Aliases are imported automatically from Google Workspace or Entra ID when Import email aliases is on; you choose which verified domains to include (Connect Entra ID, Google Workspace directory). For manually managed teammates, use Add an email alias on the profile.
• Assign a signature to the alias like any address. The right one appears based on the From address the person selects, in Gmail or Outlook (Aliases).
• The teammate table expands to show install status per address, including aliases, and can be filtered by "with aliases" (Assign teammates).
• Alias signatures are a paid-plan feature (pricing).

Microsoft 365: let people send from aliases

In Exchange Online, extra addresses on a mailbox are proxy addresses; mail sent to them is delivered to the primary mailbox (Microsoft Learn). Sending from them is off by default: unless SendFromAliasEnabled is $true, aliases on sent and received messages are rewritten to the primary address. With it on, compatible Outlook clients can send from and reply to aliases (Set-OrganizationConfig, Microsoft Learn).

Connect-ExchangeOnline
Get-OrganizationConfig | Format-List SendFromAliasEnabled
Set-OrganizationConfig -SendFromAliasEnabled $true

Microsoft notes the setting affects all messages sent and received by every mailbox, so announce it before you flip it.

Google Workspace: add the alias as "Send mail as"

A Google Workspace admin can add up to 30 alternate addresses per user at no cost, but to send from one the user must set it up as a custom From address in Gmail, and that step isn't visible in the Admin console (Google Workspace Admin Help, Gmail Help).

That missing step is the cause of Scribe's most common alias error. If the alias exists only at the admin level, Google's API returns User not found on Google Workspace when Scribe tries to install its signature, and the status shows Failed. The fix: the user (or an admin acting for them) opens Gmail Settings > See all settings > Accounts, adds the alias under Send mail as, verifies it, and Scribe pushes the signature again (Fix the user not found error for email aliases). In a large rollout, filter teammates by "with aliases" and installation "Failed" to find every case at once.

How do shared mailboxes and team inboxes get signatures?

Microsoft 365 shared mailboxes

A shared mailbox is a mailbox several people use, such as support@ or info@. It needs no license up to 50 GB, it has an underlying account that shouldn't be signed into directly, and users send from it with one of two permissions (About shared mailboxes, Manage permissions for recipients):

Permission	What the recipient sees	Signature implication
Send As	The mail appears to come from the mailbox, with no indication of the delegate	A team signature (team name, team phone) makes sense; a personal name may still be wanted
Send on Behalf	"Delegate on behalf of Mailbox"; replies go to the mailbox	The sender is visible, so a team signature plus the person's name is consistent
Full Access	Can open and manage the mailbox but not send from it	None on its own

In Scribe, Import shared mailboxes is on by default when you connect Entra ID, and imported shared mailboxes can be assigned signatures like any address (Connect Entra ID). The website pricing table lists shared mailbox signatures on every plan, including Free (pricing); the help center's plans page labels the feature "Microsoft users only" (Plans).

Both the Outlook add-in and server-side installation apply the shared mailbox's signature when someone sends from the shared mailbox (Aliases and shared mailboxes). Still include a send-as and a send-on-behalf test from each client in your pilot.

Google Workspace team addresses

Google Workspace has no direct equivalent of a shared mailbox. Teams use an alias on one person's account (one user per alias; Google recommends delegation when several people need the same address), Gmail delegation, or a Google Group as a collaborative inbox (Google Workspace Admin Help, Gmail delegation). Scribe has no shared-mailbox import for Google Workspace: add the team address as an alias on each person who sends from it, and make sure each of them also has it as a Send mail as address in Gmail, or the install fails with User not found (Aliases and shared mailboxes). Scribe doesn't document signatures for delegated mailboxes or Google Groups, so test those before planning on them.

Team inboxes in Front

If support or sales replies from a shared inbox tool, the signature has to be installed there. Scribe has a Front integration, where shared mailboxes also get their signature, matches teammates to Front users by exact email address, and notes that Front can hold more than one signature per email (User not found on Front, Installation statuses).

What happens when one address has several signatures?

Most integrations install one signature per email address. If someone is assigned more than one, only the highest-priority signature is installed and the others show Not supported; this is expected, not an error. Front and Zoho Mail can install more than one per email (Installation statuses). For Outlook users, Signature priority sets the order, and position 1 becomes the default; it doesn't apply to Gmail, where each teammate gets a single signature (Signature priority).

The practical rule: give each address exactly one signature, and use variants for context and aliases for roles, rather than assigning several signatures to one address and relying on priority.

What counts as a paid seat?

From Scribe's pricing and plan pages (pricing, Plan limits):

• A seat is a person whose primary email has at least one signature assigned.
• Alias addresses don't count as seats and are free.
• A primary email assigned to several signature templates still counts as one user.
• Syncing people doesn't bill them: sync 1,000 and assign signatures to 500, and you pay for 500.
• Deactivating a user's license in Google Workspace or Entra ID removes their signature and their seat.

Scribe's docs don't state whether a Microsoft 365 shared mailbox with a signature counts as a seat. Shared mailboxes have their own account in Entra ID, so ask Scribe before budgeting a large number of them.

How do you test replies, aliases and shared mailboxes before rollout?

Scenario	Expected result
New email to an external address	Primary signature
Reply and forward to an external address	On-reply variant (Outlook add-in or server-side); primary on client-side Gmail
New email to a colleague on the same domain	Internal variant (Outlook add-in or server-side)
Email to a colleague and an external recipient together	Primary (server-side rule: not every recipient is internal)
Email to a colleague on a sister domain	Primary (server-side rule is domain-based)
Send from an alias in Outlook and in Gmail	The alias's signature; the From address stays the alias
Send As and Send on Behalf from a shared mailbox	The shared mailbox's signature on each client you support
Long thread with ten replies	One signature per message, no stacking

Use Scribe's preview tabs to check designs first, then send real mail and check it in the recipient's mailbox. With server-side routing the sender's Sent Items copy doesn't show the signature (Scribe docs). The wider pilot plan is in the rollout playbook.

Where does Scribe fit?

Scribe handles the cases in this guide from one dashboard: reply and internal variants with their own campaign switches, unlimited free alias signatures imported from the directory, shared mailbox import from Entra ID, and install status per address. Variants work through the Microsoft 365 add-in and Microsoft 365 or Google Workspace server-side routing, and can be managed through the API as well as the editor.

Frequently asked questions

Can I use a different email signature for replies?

Yes. In Scribe each signature can have an On-Reply variant, typically a shorter design without the banner or photo. It is applied by the Microsoft 365 Outlook add-in and by server-side routing in Microsoft 365 and Google Workspace. The client-side Gmail install writes a single signature into Gmail settings, so it doesn't apply variants.

How does a signature tool know an email is internal?

With Scribe's server-side routing, a message is internal when every recipient is on the same domain as the sender, and a reply when the subject starts with a prefix such as Re:, Fw: or Fwd:, including localized ones. Everything else gets the primary signature, so a message with one external recipient, or to a sister domain, is treated as external.

Should the reply signature keep the legal disclaimer?

In most regulated organizations, yes. Replies reach external recipients just like new emails, so confidentiality or regulatory text that must appear on external mail belongs in the reply variant too. Drop the banner and photo instead.

Can each email alias have its own signature?

Yes. Scribe allows one signature for the primary address and unlimited alias signatures per person, and the signature is chosen by the From address. Aliases are imported from Google Workspace or Entra ID. In Microsoft 365, SendFromAliasEnabled must be on for users to send from aliases; in Gmail, each alias must be added as a Send mail as address.

Why does Scribe show User not found for a Google Workspace alias?

The alias exists in the Admin console but hasn't been added as a Send mail as address in the user's Gmail settings, so Google's API doesn't recognize it. Add and verify the alias under Gmail Settings, Accounts, Send mail as, then push the signature again.

Can shared mailboxes like support@ have a signature?

Yes. In Microsoft 365, Scribe imports shared mailboxes from Entra ID (the option is on by default) and lets you assign them a signature, which the Outlook add-in and server-side installation apply when someone sends from the mailbox. Shared mailboxes also work in Front. Google Workspace has no shared-mailbox import: add the shared address as an alias, set up as Send mail as, for each person who sends from it.

Do aliases or shared mailboxes cost extra?

Aliases don't: Scribe bills per person whose primary email has a signature assigned, and alias addresses are free. Several signatures on one primary email still count as one user. Scribe's docs don't state whether a shared mailbox with a signature counts as a seat, so confirm before budgeting many of them.

What if one person is assigned several signatures?

Most integrations install one signature per address, so only the highest-priority signature is installed and the others show Not supported. Signature priority sets the order for Outlook users. Front and Zoho Mail can hold more than one signature per address.

Related Handbook guides

• Microsoft 365 and Exchange Online company-wide signatures
• Google Workspace company-wide signatures
• Client-side vs server-side email signatures
• Sync signatures from Microsoft Entra ID
• Email disclaimers by country and industry