Set Up Microsoft 365 SMTP on a Multifunction Printer

A multifunction printer that cannot reliably send scanned documents by email becomes a small operational problem with an outsized cost. Staff print workarounds, IT gets repeat tickets, invoices sit in trays, and sensitive files may travel through personal inboxes. Microsoft 365 can handle scan-to-email workflows, but the right setup depends on what your printer supports, who needs to receive scans, and how tightly your tenant restricts legacy authentication. This guide explains the three practical Microsoft 365 SMTP options, how to choose between them, and how to configure a multifunction printer without creating an avoidable security exception.

Most multifunction printers need a method to hand an outgoing email to a mail server. That sounds simple until the printer is older than your Microsoft 365 security policies. Many devices only support basic username-and-password SMTP authentication, while Microsoft 365 tenants increasingly require modern authentication, conditional access rules, or stricter SMTP controls.

The business decision is not merely which server address to type into a printer menu. You need to decide whether the printer should send as a real mailbox, whether it needs to reach external recipients, whether it has a fixed public IP address, and whether scans contain sensitive information. A scan-to-email configuration should be stable enough for operations and narrow enough that a compromised printer cannot become an open relay.

There are three common approaches: authenticated SMTP client submission, Direct Send, and SMTP relay through a Microsoft 365 connector. Each can be correct. The wrong choice usually creates one of two outcomes: messages fail after a security-policy change, or the setup works too broadly and creates unnecessary exposure.

Start with recipient requirements. If staff scan documents only to colleagues using addresses in your own Microsoft 365 organization, Direct Send may be sufficient. If the printer must email suppliers, customers, accountants, or any other external address, you will generally need authenticated SMTP client submission or connector-based SMTP relay.

Then assess the device. Newer enterprise printers may support TLS, certificate validation, current cipher suites, and OAuth 2.0. Many installed multifunction devices do not. If your printer only supports a username and password, its compatibility with your tenant depends on whether SMTP AUTH is enabled and allowed by your authentication policies.

Finally, consider the network. A connector-based relay is often attractive for a fixed office location with a static public IP address. It avoids storing a mailbox password in the printer and can support external recipients. But it requires DNS and Exchange admin work. A small team with one printer may prefer a dedicated mailbox and SMTP client submission if its security policies permit it.

Option 1: SMTP client submission with a dedicated mailbox

SMTP client submission means the printer authenticates to Microsoft 365 using a mailbox address and its credentials. The standard server setting is smtp.office365.com, typically on port 587, using STARTTLS. The device sends mail as the licensed mailbox used for authentication.

This method is straightforward because it does not depend on a static IP address or custom mail-flow connector. Create a mailbox specifically for the printer, such as scanner@yourcompany.com, rather than using an employee's mailbox. That keeps ownership clear, prevents access issues when an employee leaves, and makes printer-related message tracing much easier.

The main constraint is authentication. Your organization must allow authenticated SMTP for that mailbox and device path. If security defaults, authentication policies, conditional access, or a tenant-level setting block SMTP AUTH, the printer may reject the connection even when the password is correct. Do not weaken tenant-wide controls just to accommodate one scanner; evaluate a connector relay or a modern-capable device instead.

Option 2: Direct Send for internal Microsoft 365 recipients

Direct Send lets a device send email to recipients inside your Microsoft 365 organization without authenticating with a mailbox. The printer connects to your domain's Microsoft 365 MX endpoint, usually on port 25. You can find the MX hostname in the Microsoft 365 admin center or your domain DNS records.

The advantage is simplicity: no mailbox password needs to be stored on the device. The limitation is equally important: Direct Send is designed for internal recipients. It is not the right method for sending scans directly to customers, vendors, or personal email addresses. If external delivery is a requirement, choose another route.

Direct Send also depends on network conditions. Some internet service providers and firewall policies block outbound port 25. Before you spend time changing printer settings, confirm that the office network can reach the Microsoft 365 MX endpoint. A quick firewall review can save an afternoon of guessing at SMTP credentials that were never the issue.

Option 3: Microsoft 365 SMTP relay through a connector

SMTP relay uses an Exchange Online connector that trusts mail from your organization's network. The connector validates the sending source using a static public IP address or, in some scenarios, a TLS certificate. The printer then sends mail through your Microsoft 365 MX endpoint, commonly over port 25.

This is often the stronger operational design for offices with several printers, scanners, line-of-business systems, or building devices that need to email external recipients. You avoid keeping a user password in every device, and the connector can be restricted to known network sources. It does require more setup discipline than SMTP client submission.

Do not treat connector relay as a shortcut around security. Restrict the connector to the exact public IP addresses you control, document the sending devices, and periodically review mail flow. If your office uses a changing public IP address, connector relay can become unreliable unless your internet provider can provide a static address.

Gather the inputs before configuring anything. You need the sending address, the chosen delivery method, the SMTP server hostname, port, encryption requirement, and authentication method. You should also know the printer's firmware version, its DNS server configuration, and whether it validates TLS certificates correctly.

For SMTP client submission, create and document a dedicated mailbox. Confirm it can sign in, has an Exchange Online mailbox license where required, and is permitted to use authenticated SMTP. Use a long unique password stored in your password manager, not a shared spreadsheet or a label on the printer.

For Direct Send or SMTP relay, obtain the domain MX endpoint from Microsoft 365 rather than assuming it is smtp.office365.com. Those options use a hostname that typically resembles your domain's protection endpoint. Also record your office's public IP address if you are creating an IP-restricted connector. Be precise: a private address such as 192.168.x.x is not what Exchange Online sees.

Open the printer's web-based administrator interface. The exact labels vary by manufacturer, but look for Email, SMTP, Scan to Email, Outgoing Mail Server, or Network Services. Update the printer firmware first if it is significantly behind; older firmware can fail TLS negotiation with current cloud mail services.

Enter smtp.office365.com as the SMTP server and 587 as the port. Select STARTTLS or TLS where the device uses that wording. Enable SMTP authentication, then enter the dedicated scanner mailbox address as the username and the associated password. Set the From address to that same mailbox unless your device and Microsoft 365 permissions are explicitly configured for a different sender.

Send a test scan to an internal mailbox, then an approved external test recipient if external delivery is part of the requirement. Check the received message for the expected From address, subject line, attachment, and timestamp. If the printer reports success but no email arrives, use Exchange message trace to determine whether Microsoft 365 accepted, filtered, quarantined, or rejected the message.

Recommended settings for SMTP client submission

Some printer interfaces offer SSL on port 465 as a default. Do not assume that setting is interchangeable with Microsoft 365 client submission. Follow the documented settings supported by your device and Microsoft 365 configuration. When in doubt, use port 587 with STARTTLS for SMTP client submission rather than cycling randomly through ports.

For Direct Send, point the printer to your Microsoft 365 MX endpoint and use port 25. Do not enable mailbox authentication. Configure an internal From address that belongs to your accepted domain, such as scanner@yourdomain.com. Test delivery to a colleague in the same Microsoft 365 tenant first.

For SMTP relay, create an inbound connector in the Exchange admin center that identifies mail from your organization by its static public IP address or certificate. Limit the permitted source as tightly as possible. Then configure the printer with your Microsoft 365 MX endpoint and port 25. Authentication is generally not configured on the device because the trust decision occurs at the connector level.

Both methods benefit from a clear sender policy. Use a recognizable address, add a useful subject prefix such as “Scan from Accounts Printer,” and set a sensible maximum attachment size. A vague sender name and 25 MB scans make support harder than it needs to be. Configure scan resolution and color defaults to produce files people can actually receive and open.

A multifunction printer is a networked computer with a touchscreen, storage, address book, and sometimes a web server that nobody checks after installation. Change its default administrator password, restrict administration to the internal network, and disable protocols you do not use. If the device supports role-based administration, avoid giving every office manager full device-admin access.

Use a dedicated sender identity and give it only the permissions it needs. Do not use a global administrator account, a CEO's mailbox, or a shared password that also grants access to other systems. If the device stores an SMTP password, treat a printer replacement or disposal as a credential rotation event.

Also think about who can initiate a scan. Address-book access, walk-up scanning, saved destinations, and automatic forwarding can expose confidential documents. A finance printer that can email any arbitrary external address may be convenient, but convenience needs a counterweight: access control, audit logs, recipient restrictions, or an approval process where the risk warrants it.

An “authentication failed” message often points to more than a typo. Confirm the dedicated mailbox credentials, then check whether SMTP AUTH is enabled for that mailbox and permitted under your tenant's authentication configuration. Review sign-in logs where available. A blocked legacy-auth attempt is a policy issue, not a printer-password issue.

A timeout or connection failure usually means DNS, firewall, ISP, or TLS trouble. Verify the printer can resolve the SMTP hostname, that outbound port 587 or 25 is allowed for the chosen method, and that the device date and time are correct. A substantially incorrect device clock can cause certificate validation failures.

If internal scans deliver but external scans fail, revisit the method you chose. Direct Send is intentionally limited for this use case. If a connector relay accepts mail but delivery is inconsistent, confirm the connector's public IP restriction matches your current office egress IP. Internet failover connections can quietly change that address and break a previously healthy configuration.

Use logs instead of guessing

Ask the printer for its SMTP error code and retain the full message. Codes and server responses often identify whether the failure happened before connection, during TLS negotiation, during authentication, or during recipient validation. “Cannot connect” and “authentication unsuccessful” demand different fixes.

On the Microsoft 365 side, use message trace for delivery questions and review connector configuration for relay questions. If there is no trace of the message, the printer likely did not reach Exchange Online. If there is a trace, Microsoft 365 can show whether the message was rejected, quarantined, or delivered.

This approach mirrors good operations work more broadly: define the handoff, observe the failure point, and change one variable at a time. The same discipline matters when a business connects marketing forms, CRM routing, outbound systems, and reporting. An operator model works best when ownership and system boundaries are explicit. Anton Chisliuk · AI Marketing Ops applies that approach to growth systems, with one senior operator handling the workflow rather than passing issues through account layers; for example, Cleverence grew from 0 to 80K organic visits per month through coordinated SEO operations.

Do not spend unlimited labor preserving a device that cannot meet your organization's baseline security requirements. If the printer cannot support TLS reliably, cannot validate modern certificates, requires unsupported authentication behavior, or has no vendor security updates, replacement may be less expensive than recurring troubleshooting.

Compare the cost honestly. A new multifunction printer has a visible capital or lease cost. An old device has hidden costs: repeated helpdesk time, insecure exceptions, delayed document processing, failed scans, and employee workarounds. The right choice is not automatically the newest hardware; it is the option with the lower operational burden and acceptable risk.

For larger offices, standardize the setup pattern across devices. Use consistent sender addresses, a documented relay design, device inventory, firmware review dates, and a named owner. That turns scan-to-email from a collection of one-off fixes into an operational service that survives staff changes and office moves.

Before go-live, confirm that you have selected SMTP client submission, Direct Send, or connector relay based on actual recipient requirements. Create a dedicated mailbox only when the chosen approach needs one. Document the SMTP hostname, port, TLS setting, sender address, and the person responsible for credential or connector maintenance.

Test the workflow from the printer itself, not only from a desktop email client. Send a small PDF internally, then externally if external delivery is intended. Test a realistic scan size, review the sender display name, and verify that recipients can reply to the address if that is useful to your process.

After deployment, put the configuration in your IT runbook. Include admin access location, firmware version, IP address, public IP dependency, mailbox ownership, and the date of the last test. This may feel excessive for a printer until the device fails during payroll, month-end billing, or a compliance deadline. Then the runbook becomes cheap insurance.

One printer and one office usually do not require a large consultancy. A capable IT administrator can configure the right Microsoft 365 method, test it, and document it. The complexity rises when the printer is part of a larger workflow: scans create CRM records, trigger customer communications, route into document storage, or feed approval automation.

At that point, email configuration is one link in a business process. The useful question is whether the handoff is reliable, observable, secure, and connected to the system where work actually gets done. A document sent to an inbox is not necessarily a process. It may still need routing, data extraction, a record owner, and an SLA.

If your growth and operations systems are accumulating similar manual handoffs, a structured Growth Audit can help identify where CRM, automation, acquisition, and reporting workflows are breaking down. The goal is not more software. It is fewer avoidable gaps between a customer action and a team response.

Microsoft 365 SMTP on a multifunction printer works best when you choose the method before touching the device settings. Use SMTP client submission when a dedicated mailbox and authenticated sending fit your tenant policies. Use Direct Send for internal-only Microsoft 365 delivery. Use a connector-based relay when you need external sending from a controlled office network with a static public IP.

Keep the design narrow: dedicated identities, TLS where supported, restricted connectors, current firmware, and documented tests. That protects the business from a surprisingly common operational failure point while making support far less dependent on one person remembering what was configured years ago.

If scan-to-email is one symptom of wider disconnected systems, the practical next step is to request a Growth Audit and map the workflows that are costing your team time.

- What is the Microsoft 365 SMTP server for a multifunction printer?

For authenticated SMTP client submission, use smtp.office365.com with port 587 and STARTTLS. Direct Send and connector-based relay generally use your Microsoft 365 MX endpoint on port 25 instead.

- Can a Microsoft 365 printer send email without a mailbox password?

Yes. Direct Send can send to internal Microsoft 365 recipients without mailbox authentication, and connector-based SMTP relay can trust a known public IP address or certificate. Both require the right network and Exchange configuration.

- Why does my printer say SMTP authentication failed with Microsoft 365?

Check the mailbox credentials first, then verify that SMTP AUTH is allowed for the mailbox and not blocked by tenant security settings, authentication policies, or conditional access. Also confirm the printer supports the required TLS configuration.

- Can Direct Send email external recipients?

Direct Send is intended for internal recipients in your Microsoft 365 organization. If your printer needs to email external addresses, use SMTP client submission or a properly configured Microsoft 365 connector relay.

- Should I use an employee mailbox for scan-to-email?

No. Use a dedicated mailbox or a connector-based relay. An employee mailbox creates ownership, offboarding, security, and troubleshooting problems that are easy to avoid.

- What port should I use for Microsoft 365 SMTP relay?

Connector-based SMTP relay commonly uses port 25 to your Microsoft 365 MX endpoint. SMTP client submission typically uses port 587 with STARTTLS. Confirm firewall and ISP rules for the method you choose.

- How do I find my Microsoft 365 MX endpoint?

Find your domain's MX record in the Microsoft 365 admin center or through DNS lookup tools. Use the exact endpoint assigned to your domain for Direct Send or connector-based relay rather than guessing the hostname.

- Is SMTP client submission safe for a printer?

It can be safe when the printer supports current TLS, uses a dedicated mailbox with a unique password, and SMTP AUTH is allowed under your security policy. If the device is old or cannot meet those controls, connector relay or hardware replacement may be the better choice.