Outlook and Microsoft 365: IMAP, SMTP and app passwords

Outlook is the mailbox that most often fails to connect, and it is almost always one of three reasons.

Pick the right preset in Settings > Mailbox:

• Microsoft 365 / Office 365 (business): IMAP outlook.office365.com:993 (SSL), SMTP smtp.office365.com:587 (STARTTLS).
• Outlook.com / Hotmail (personal): IMAP outlook.office365.com:993 (SSL), SMTP smtp-mail.outlook.com:587 (STARTTLS).

Why a password is rejected:

1. Basic authentication is disabled. Microsoft has switched most business tenants to OAuth only. Use the "Connect Microsoft" button in the mailbox panel, or ask your admin to enable SMTP AUTH and IMAP for that mailbox in the Microsoft 365 admin center.
2. Two-step verification is on. Personal Outlook.com and Hotmail accounts need an app password: account.microsoft.com > Security > Advanced security options > App passwords. Paste that password, not your normal one.
3. The wrong port or encryption. SMTP must be 587 with STARTTLS; port 465 with implicit SSL is not offered by Outlook.

If the connection fails, EspressoDesk shows this guidance directly under the form so you can fix it without leaving the page.