Close

Close connects each person's Microsoft 365 account and sends their email through it, and Footer365 signs mail that passes through your Microsoft 365. Choose how your CRM or app sends its mail explains the two ways to send, and this guide follows the first.

At a glance

• Can be signed: email sent through a person's connected Microsoft 365 account. Close's connection page says a disconnect on sending "usually means that your SMTP (email sending) is not enabled on your Office365 mailbox for 3rd party apps like Close". Workflow (sequence) email can be sent from a connected account too.
• Cannot be signed: Close's pages read do not describe any email Close sends from its own servers, so check one message of each kind you send, including bulk email.
• How it connects: a Microsoft sign-in, with SMTP and IMAP turned on for the mailbox. Close's page does not say which protocol it uses to send or whether it uses OAuth.
• Status: from Close's documentation as read on 23 October 2026, not tested by Footer365.

Before you start

• Footer365 mail flow is set up. With the Outlook add-in only, no mail Close sends is signed. Using the Outlook add-in only
• Every person who sends from Close has a Footer365 signature rule that covers them.
• Authenticated SMTP and IMAP are on for each mailbox that connects, as in step 1.

Step 1: Approve the app in Microsoft 365

1. Turn on Authenticated SMTP for the mailbox, in the Microsoft 365 admin center under Users > Active users, then Mail > Manage email apps, or with Exchange Online PowerShell: Set-CASMailbox -Identity [email protected] -SmtpClientAuthenticationDisabled $false. Turn on SMTP sign-in for one mailbox
2. Turn on IMAP under Mail > Manage email apps, save, and add the account again in Close.
3. Approve Close in Microsoft. If Microsoft shows an "Administrator approval required" screen, Close calls it "an app consent issue in your organization's Microsoft tenant", and an administrator must approve Close's permissions first. Approve an app's access in Microsoft 365

Close says calendar permissions "are required to complete the connection even if you don't plan to use calendar syncing", and that in August 2026 it updated its app registration with Microsoft, so reconnecting may show a new approval prompt for calendar permissions.

Step 2: Choose the mailbox

• Each person's own mailbox. The mail is signed with the signature your rules give that person. Close says most plans let each user connect up to 10 connected accounts, and the legacy Solo, Essentials and Base plans up to 3.
• A shared mailbox: Close's page does not cover it. Do not assume it works.
• Matching addresses. Close says that if sent email does not appear in the Office365 folder, you should make sure the Office365 primary email address and username match the email address in Close.

Step 3: Connect it in Close

1. In Close, go to Settings > Accounts & Apps > + Add Account > Microsoft.
2. Sign in with the Microsoft 365 account and approve the access Microsoft asks for.

Close's own steps: Office 365 connected accounts and Email configuration.

Step 4: Check one message

1. Send an email from Close to an address outside your organisation that you can read.
2. Open the headers of the copy you receive.
3. Return-Path should be the sender's own address, and X-Footer365-Relay-Id should be there.
4. Look in the sender's Sent Items. Close says sent email may not appear there when the primary address and the username differ, as in step 2.

Check a workflow email as well. What other results mean: Mail from our CRM is not signed.

Where the signature goes

Close has its own signature setting: "You'll also want to set up your email signature under Settings > Email > Email Signature." If people also set one there, their messages would carry two signatures, Close's and Footer365's. Leave it empty if the signature should come from Footer365 alone.

To have Footer365's signature where Close puts its own, write the text marker {{Footer365 signature here}} in that setting instead of leaving it empty, and Footer365 puts the signature where the marker is. See Place the signature with a marker. Close's documentation does not say what its signature setting does with text in double braces, so check one message: the received copy should carry Footer365's signature where the marker was, and no marker. A message that does not pass through Footer365 shows the marker as it was written.

What is not signed

Close's pages read do not describe email that Close sends from its own servers, such as bulk email, so check one message of each kind you send. Close says that removing an account without replacing the email sending account causes active workflows "to be automatically moved to the first (oldest) connected account that has email sending enabled", so workflow email stays on a connected mailbox, though not necessarily the one you expect.

What stops working

Close's pages read do not mention OAuth, Microsoft Graph, Basic authentication or the end of December 2026. Close needs Authenticated SMTP, and Microsoft has announced that Basic authentication for SMTP is turned off by default for existing organisations at the end of December 2026. If Close's mail stops sending then, reconnect the account and ask Close which sign-in it uses. Turn on SMTP sign-in for one mailbox

Limits

Close's pages state no sending limit for a connected Microsoft account. Microsoft's limits for a mailbox apply: 10,000 recipients a day and 30 messages a minute. Microsoft: Exchange Online limits

Last resort: a connector to Exchange Online

Close's pages describe no connector from Close into Exchange Online, and Close runs on its own servers. Microsoft says SMTP relay cannot be used for a service hosted by someone else, and asks such a service for a certificate of your own. So there is no connector route for Close mail. Last resort: a connector to Exchange Online

If it does not work

1. The account disconnects whenever someone sends. Close says to reset SMTP access: turn Authenticated SMTP on for the mailbox, as in step 1.
2. Microsoft shows "Administrator approval required". Approve an app's access in Microsoft 365
3. The message has no X-Footer365-Relay-Id. It did not pass through Microsoft 365.
4. It passed through Footer365 but is unsigned. The signature was not added
5. Still not clear. Mail from our CRM is not signed

Sources

Read on 23 October 2026. Close's pages show no date.

• Close: Office 365 connected accounts
• Close: Email configuration