Zoho CRM

Zoho CRM lets a person connect their Microsoft 365 mailbox and send 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 a person sends from Zoho CRM after connecting their Office 365 or Outlook mailbox in Email Configuration. Zoho's troubleshooting page treats sending as SMTP, and fixes a sending error by turning Authenticated SMTP on in Microsoft 365. It does not say in so many words that every kind of Zoho email uses the mailbox.
• Cannot be signed: anything Zoho sends from its own servers. Zoho says that if its Email Relay cannot deliver mail from your relay server, "they will be sent via Zoho CRM's server". Where mass email is sent from is not stated, so assume it is not signed until a test message shows otherwise.
• How it connects: "Office 365, Outlook, and Gmail users can log in to their accounts using OAuth." Whether the SMTP sending then uses OAuth or a stored password is not stated.
• Status: from Zoho'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 Zoho sends is signed. Using the Outlook add-in only
• Every person who sends from Zoho has a Footer365 signature rule that covers them.
• Authenticated SMTP is turned on for each mailbox that connects, as in step 1.

Step 1: Approve the app in Microsoft 365

Zoho's pages read do not list the Microsoft permissions it asks for, or say whether an administrator must approve them. If a person is told approval is needed, approve it by one of the three ways in Approve an app's access in Microsoft 365.

Zoho's troubleshooting page gives one Microsoft 365 setting for sending. Its error "Unable to get SMTP email" is fixed by turning Authenticated SMTP on for the mailbox: in the Microsoft 365 admin center, go to Users > Active users, select the user, select Mail, then Manage email apps, check Authenticated SMTP and Save changes. Zoho adds that the person's User Principal Name and email address must match in your identity provider. Turn on SMTP sign-in for one mailbox

Step 2: Choose the mailbox

• Each person's own mailbox is what Email Configuration connects. The mail is signed with the signature your rules give that person.
• A shared mailbox: Zoho's pages read do not say whether one can be connected. Do not assume it works.
• Organisation email address. Zoho's mass email page lets the From be the record owner's address or the "Organization's email address, if already configured." Footer365 signs only an address it finds in your directory, so a rule must cover any organisation address you use.

Step 3: Connect it in Zoho CRM

Following Zoho's steps:

1. Go to Setup > Channels > Email > Email Configuration.
2. In the Email sub-tab, select Get Started.
3. In the Email Integration tab, choose Office 365 or Outlook from the popular email services, and choose the protocol, IMAP or POP.
4. Select Configure, then sign in to the Microsoft account and select Next.

Zoho's own steps: Email configuration for IMAP and POP3.

Step 4: Check one message

1. Send an email from Zoho CRM 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. Zoho's page does not say sent mail is saved there, so its absence is not a fault by itself.

Check one message of each kind you send, including mass email. What other results mean: Mail from our CRM is not signed.

Where the signature goes

Zoho's pages read do not describe a signature setting for connected mailboxes. If you see two signatures, remove Zoho's. To place Footer365's signature in a template, use a marker, and check one message, because Zoho's pages do not say what it does with text in double braces. Place the signature with a marker

What is not signed

• Mass email. Zoho's page does not say where mass email is sent from. Its limit "depends on the email limit specific to your Zoho CRM edition", and Zoho allows up to 10 mass emails to be scheduled at a time. Check one message before relying on it being signed.
• Email Relay mail that falls back. Zoho says: "If the outbound emails fail to deliver from the relay server for any reason, they will be sent via Zoho CRM's server." That mail leaves from Zoho and is not signed.

What stops working

Zoho's pages read do not mention Exchange Web Services. Sending 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. Zoho says people can log in with OAuth, but does not say the SMTP sending uses it. If a person's Zoho mail stops sending at the end of December 2026, reconnect the mailbox and ask Zoho which sign-in it uses. Turn on SMTP sign-in for one mailbox

Limits

Zoho's limits depend on your edition and the pages read do not give them for connected mailboxes. 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

Zoho's Email Relay hands CRM mail to a relay server. Zoho's troubleshooting page says relay "work[s] based on the domain, not based on the user email addressed", and does not mention Microsoft 365 or Exchange. If that server is Exchange Online, Microsoft says SMTP relay cannot be used for a service hosted by someone else, and Zoho's CRM servers are one. Zoho also says relay failures fall back to its own servers, unsigned. Do not set Email Relay up for Exchange Online unless Zoho documents it. Last resort: a connector to Exchange Online

If it does not work

1. "Unable to get SMTP email". Turn Authenticated SMTP on for the mailbox. Zoho says that if it is already on, turn it off and on again, then save.
2. A scope error. Zoho names the error "The provided resource value to the input parameter 'scope' is not valid", and says to configure the Microsoft account that matches the provider you chose, Outlook or Office 365.
3. "User is authenticated but not connected". Zoho says this can happen when the IMAP connection limit is passed.
4. The message has no X-Footer365-Relay-Id. It did not pass through Microsoft 365. It may be mass email or Email Relay fallback.
5. It passed through Footer365 but is unsigned. The signature was not added
6. Still not clear. Mail from our CRM is not signed

Sources

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

• Zoho: Email configuration for IMAP and POP3
• Zoho: Troubleshooting IMAP and POP3 configuration
• Zoho: Sending mass emails
• Zoho: Troubleshooting Email Relay