# Connect your Microsoft 365 mailbox > What you need, how to get the password, and the exact settings to type so your office can send and read e-mail through your Microsoft 365 mailbox. Your office sends and reads e-mail through your own business mailbox — never a shared address, and never without your approval. This page takes you from nothing to a working Microsoft 365 mailbox. Everything here is the same information the **Need help?** drawer on the Connectors page shows you, drawn from the same place, so the two can never disagree. ## What you need - The full e-mail address of the mailbox your office should send from, and the ability to sign in to it. - Someone with administrator rights on your Microsoft 365 account. The first step below cannot be done by anyone else — if that is not you, send them this page. - The mailbox’s own sign-in password — this provider issues no separate app password for it. - Your business postal address, and the reason you are allowed to write to the people your office will contact. The form asks for both before it will let you save, so have them to hand — see "Finish the form, in this order" below. > If you would rather not type settings at all, the Connectors page offers a sign-in button for Microsoft 365 under **Connect your business mailbox**. Where that button has not been set up it reads **Not available yet** — and then the steps below are the path that works everywhere. ## Getting your password 1. An admin must confirm authenticated SMTP submission (SMTP AUTH) is turned on for this specific mailbox: Microsoft 365 admin center → Users → Active users → select the user → Mail → Manage email apps → check "Authenticated SMTP" → Save changes. 2. If the organization has "Security defaults" turned on in Microsoft Entra, SMTP AUTH will still be blocked even after the step above — the admin needs to turn that off, or use a Conditional Access exception, before this will work. 3. Use the mailbox's full email address and its normal sign-in password (Microsoft 365 does not use a separate "app password" scheme for this the way Google does) in the mailbox settings in the next section. ## The settings to enter On the Connectors page, find **Email connector**. The button that opens the form reads **Advanced: SMTP / IMAP** if you have never connected a mailbox, and **Change connector** if one is already connected — both open the same form, and the form itself is headed **SMTP / IMAP**. | Setting | SMTP (outgoing) | IMAP (incoming, optional) | | --- | --- | --- | | Host | `smtp.office365.com` | `outlook.office365.com` | | Port | `587` | `993` | | Username | The mailbox’s full e-mail address | The same full e-mail address | | Password | The mailbox’s own sign-in password | The same password | Encryption: `STARTTLS (TLS 1.2/1.3) — NOT port 465` for outgoing mail, `SSL/TLS` for incoming. Leave **Use TLS** ticked on both halves of the form. The outgoing fields are labelled **SMTP host**, **Port**, **Use TLS**, **Username** and **Password**. Incoming mail is optional: tick **Also configure IMAP (optional)** to reveal **IMAP host**, **IMAP port**, **Use TLS**, **Username** and **Password**. Your office can send without it, but it can only read replies once incoming mail is set up. ## Finish the form, in this order The mail settings above are not the whole form. Two more answers are required before it will save, and two buttons finish the job: 1. **Confirm your business postal address.** Required by law on business e-mail, not by us — it appears at the bottom of everything your office sends. 2. **Choose your legal basis for contacting these people.** Pick the option that matches how you got your contacts. The form says so itself: most small businesses choose "They are a potential customer for our business", and that is the default rather than a requirement. 3. **Save connector.** If saving does nothing, the postal address is the field to check first — an empty one blocks the save and the page says so above the box. (Your legal basis cannot block it: the form starts with an option already chosen.) 4. **Test connection.** Until you do, the mailbox reads **Waiting for verification**: drafts still work, but sending needs it. ## Good to know - Microsoft is retiring Basic-auth SMTP AUTH client submission — as of this writing it is being disabled by default for many tenants and Microsoft is actively pushing everyone to sign in with Microsoft instead. The manual SMTP / IMAP form on the Connectors page may simply stop being accepted by Microsoft at some point; if sending suddenly fails with an authentication error on the Connectors page, that is very likely why. The fix is the sign-in button under Microsoft 365 in the "Connect your business mailbox" section of the Connectors page — no setting on that form resolves it. - Never use port 465 for Microsoft 365 SMTP — Microsoft's own documentation states a client defaulting to 465 does not support the TLS version their servers require; use 587. ## Where these settings come from Every fact on this page was checked on 2026-08-04 against the documentation Microsoft 365 publishes itself. Providers do move these things. If what you see on screen no longer matches what is written here, their own pages are the authority: - - Still stuck? The Connectors page has a **Need help?** button, and inside it a **Still stuck? Ask the CEO** button that hands the question to your CEO, naming the provider you were reading about.