Ask your Microsoft 365 administrator first

This is for work or school Exchange Online mailboxes, including Microsoft 365 purchased through GoDaddy. Standard IMAP and POP access require modern OAuth authentication. AeroMailer currently uses password authentication for these connections and cannot sign in to OAuth-only mailboxes. For SMTP, an administrator must confirm that the mailbox is explicitly permitted to use authenticated SMTP and that password-based sign-in is still permitted by current tenant policy. Never disable security defaults, MFA, or Conditional Access just to connect.

Find the Exchange Online server details

  1. Confirm that the mailbox is hosted in Exchange Online. Ask your administrator for its exact sign-in name and authorized From address.
  2. For a compatible OAuth client, standard IMAP is outlook.office365.com, 993, SSL/TLS. That endpoint is listed here for reference; the AeroMailer preset does not add OAuth.
  3. For authorized SMTP client submission, use smtp.office365.com, 587, STARTTLS. Your admin can verify mailbox SMTP AUTH under Users → Active users → Mail → Manage email apps. A checked setting does not override organization authentication policy.

When AeroMailer can send

Only if your administrator confirms that the existing policy permits password SMTP AUTH, choose Microsoft 365 / Office 365 → SMTP only in Add Account, enter the approved credentials, run Test Connection, then send a test to yourself. If the mailbox requires OAuth or SMTP AUTH is unavailable, use an administrator-approved, AeroMailer-compatible SMTP service or relay instead. Use a Microsoft-compatible client to read the Exchange Online mailbox.

Sources: Exchange Online authentication, mailbox SMTP AUTH settings, Microsoft server settings, and the current retirement timeline.