Setting up SMTP with Outlook

Follow this guide if you want to send Purchase Orders to your suppliers from your own Outlook address instead of the app's default sender address.

Time needed: about 10 minutes (add ~5 minutes if you use a Microsoft 365 company email and need your IT administrator's help).

Before you start

Check which type of Outlook account you have — the SMTP server is different for each:

Account type	Example address	SMTP host to use
Personal Outlook (free)	[email protected], @hotmail.com, @live.com	smtp-mail.outlook.com
Microsoft 365 / company email	[email protected] (paid Microsoft 365 Business plan)	smtp.office365.com

Not sure which one you have? Sign in at https://outlook.office.com. If it works, you have a Microsoft 365 (company) account. If you are redirected to https://outlook.live.com, you have a personal account.

You will need sign-in access to that Outlook account. For a company email, your IT administrator may need to do Step 3 for you.

Step 1 — Turn on two-step verification

Microsoft only lets you create an app password after two-step verification is enabled on the account.

1. Go to https://account.microsoft.com/security and sign in.

2. In the Account Security box, click the Manage how I sign in button.

   This is the page that used to be called Advanced security options — Microsoft renamed it and moved it behind this button. You can also go there directly: https://account.live.com/proofs/manage/additional

3. Find Two-step verification and click Turn on, then follow the prompts (verification by phone number or the Microsoft Authenticator app).

Microsoft 365 company email: this page may not show Two-step verification at all, because security is managed by your organization. Ask your IT administrator to enable multi-factor authentication (MFA) and allow app passwords for your mailbox.

Expected result: Two-step verification shows the status On.

Step 2 — Create an app password

An app password is a separate password for applications — it is not your everyday sign-in password. Using your normal password here will be rejected by Microsoft.

1. Stay on the page you opened with Manage how I sign in and scroll to the bottom to the App passwords section.

   Don't see App passwords? Two-step verification in Step 1 is almost certainly still off. This section only appears once two-step verification is On — finish Step 1, then reload the page.

2. Click Create a new app password.

3. Microsoft shows a string of characters — copy and save it right away. Once you close the window, you cannot view it again.

Expected result: you have an app password (usually 16 characters).

Step 3 — Enable Authenticated SMTP (Microsoft 365 company email only)

Skip this step if you use a personal Outlook account.

Microsoft blocks SMTP sending on company mailboxes by default. An administrator has to unblock it:

1. Sign in to the Microsoft 365 Admin Center → Exchange admin center (https://admin.exchange.microsoft.com).
2. Go to Recipients → Mailboxes and select the mailbox you will send from.
3. Open the Settings tab, or Manage email apps.
4. Tick Authenticated SMTP and click Save.

The equivalent PowerShell command, if your administrator prefers it:

Set-CASMailbox -Identity [email protected] -SmtpClientAuthenticationDisabled $false

Expected result: the Authenticated SMTP checkbox is ticked.

Step 4 — Enter the details in the app

1. Open Mimoran: Purchase Order Plus in your Shopify admin.
2. Go to Setting → SMTP Configuration.
3. Fill in the fields:

Field in the app	Personal Outlook	Microsoft 365 (company email)
Use SMTP to send email	Yes	Yes
Host	smtp-mail.outlook.com	smtp.office365.com
Port	587	587
Username	your full email address, e.g. [email protected]	your full email address, e.g. [email protected]
Password	the app password from Step 2	the app password from Step 2

4. Click Save.

About the port: use 587 only. The app sends over STARTTLS, so port 465 will not connect.

Expected result: the fields are saved and Use SMTP to send email shows Yes.

Step 5 — Make the sender address match the Outlook account

This is the most common mistake: Outlook does not allow you to send mail on behalf of an address other than the account you signed in with.

1. Still in Setting, open the Email tab (the sender settings used for supplier emails).
2. Set Email contact address to exactly the address you entered in the Username field in Step 4.
3. Click Save.

Example: if the username is [email protected], the email contact address must also be [email protected]. If you leave it as [email protected], Outlook will block the message.

Expected result: both addresses match exactly.

Step 6 — Send a test email

1. Open any Purchase Order (or create a draft PO to test with).
2. Click Send email to supplier, but put your own email address as the recipient.
3. Check your inbox.

Expected result: the email arrives and the sender shows your Outlook address.

If nothing arrives, see the troubleshooting table below.

Troubleshooting

Error message	Cause	How to fix
535 5.7.139 ... SmtpClientAuthentication is disabled	Authenticated SMTP is not enabled on the Microsoft 365 mailbox	Redo Step 3 (ask your administrator)
5.7.57 Client not authenticated to send anonymous mail	Wrong username or password	Recheck Step 2 — you must use the app password, not your sign-in password
5.7.60 SendAsDenied	Sender address differs from the SMTP account	Redo Step 5
Cannot reach the server / long hang, then an error	Wrong port or host	Recheck Step 4 — the port must be 587
Email is delivered but lands in the supplier's spam folder	SPF/DKIM not configured for your domain	Ask your IT team to add SPF/DKIM records for the company domain

Outlook sending limits

Outlook enforces daily sending limits, and sending is temporarily blocked once you exceed them:

• Personal Outlook: about 300 recipients per day.
• Microsoft 365: about 10,000 recipients per day, and roughly 30 emails per minute.

If your store sends purchase orders to a large number of suppliers each day, consider a dedicated email sending service instead of Outlook.

Important note about Microsoft's timeline

Microsoft is phasing out password-based sign-in for SMTP:

• End of December 2026: Microsoft turns this method off by default for existing Microsoft 365 accounts (administrators can still re-enable it). Company accounts created after that date will not have it available.
• Second half of 2027: Microsoft will announce the final shutdown date.

The setup in this guide still works today, but in the long run you should plan to move to another option (OAuth sign-in, the Microsoft Graph API, or a dedicated email sending service). The Mimoran team will let you know when the app supports a new method.

Need help?

If you have followed every step and still cannot send, send our support team:

1. Your account type (personal or Microsoft 365).
2. A screenshot of Setting → SMTP Configuration (hide the password).
3. The exact error message shown when you send a test email.