The Microsoft 365 SMTP, IMAP and POP3 settings you need — server smtp.office365.com, port 587 (STARTTLS). Copy each field with one click. Free, with no signup.
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Microsoft 365 mail settings
Outgoing mail (SMTP)
SMTP server
smtp.office365.com
Port — STARTTLS
587
Security
STARTTLS on 587. Port 465 (SSL/TLS) is not supported for Microsoft 365 SMTP AUTH.
Incoming mail (IMAP)
IMAP server
outlook.office365.com
Port — SSL/TLS
993
Incoming mail (POP3)
POP3 server
outlook.office365.com
Port — SSL/TLS
995
Sending limits & login
Daily send limit
Up to 10,000 recipients per day and 30 messages per minute per mailbox.
Authentication
SMTP AUTH must be enabled on the mailbox by a Microsoft 365 admin — it is off by default on many tenants. Microsoft has disabled Basic Authentication for IMAP and POP on Exchange Online, so those protocols now require OAuth/modern auth on most tenants and an app password often will not connect.
App password
Use an app password if security defaults or MFA are enforced and SMTP AUTH still allows Basic Auth; otherwise the client must sign in with modern auth (OAuth).
For business Microsoft 365 / Exchange Online mailboxes on a custom domain. GoDaddy, and many resellers, sit on these same servers.
Sending cold email? EmailChaser manages inboxes, warmup and deliverability for you.
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To send email through Microsoft 365, set your outgoing (SMTP) server to smtp.office365.com and use port 587 (STARTTLS). STARTTLS on 587. Port 465 (SSL/TLS) is not supported for Microsoft 365 SMTP AUTH.
For incoming mail, use the IMAP server outlook.office365.com on port 993, or POP3 at outlook.office365.com on port 995. Pick the exact values from the tool above and copy them straight into your mail client.
Up to 10,000 recipients per day and 30 messages per minute per mailbox. SMTP AUTH must be enabled on the mailbox by a Microsoft 365 admin — it is off by default on many tenants. Microsoft has disabled Basic Authentication for IMAP and POP on Exchange Online, so those protocols now require OAuth/modern auth on most tenants and an app password often will not connect. Use an app password if security defaults or MFA are enforced and SMTP AUTH still allows Basic Auth; otherwise the client must sign in with modern auth (OAuth).
Those caps make single-mailbox sending fine for personal mail but a poor fit for cold outreach at volume. Emailchaser spreads sending across warmed inboxes and manages deliverability, so you can scale without burning Microsoft 365 accounts.
What are Microsoft 365's SMTP settings?
Microsoft 365's outgoing (SMTP) server is smtp.office365.com. Use port 587 (STARTTLS). STARTTLS on 587. Port 465 (SSL/TLS) is not supported for Microsoft 365 SMTP AUTH. Sign in with your full email address and password (or app password).
What is Microsoft 365's IMAP or POP3 server?
Microsoft 365's incoming IMAP server is outlook.office365.com on port 993 (SSL/TLS). If you prefer POP3, use outlook.office365.com on port 995.
Which port should I use for Microsoft 365?
Use port 587 with STARTTLS wherever it's offered — it's the modern standard for authenticated sending. Port 465 with SSL/TLS is a solid alternative. Avoid port 25, which most networks block for client sending. Microsoft 365's recommended value is above.
Why won't my Microsoft 365 SMTP connection work?
Check authentication first: SMTP AUTH must be enabled on the mailbox by a Microsoft 365 admin — it is off by default on many tenants. Microsoft has disabled Basic Authentication for IMAP and POP on Exchange Online, so those protocols now require OAuth/modern auth on most tenants and an app password often will not connect. Use an app password if security defaults or MFA are enforced and SMTP AUTH still allows Basic Auth; otherwise the client must sign in with modern auth (OAuth). Then confirm the host, port and security method match exactly — a 587/SSL or 465/STARTTLS mismatch will fail to connect.
Can I send bulk or cold email through Microsoft 365?
Not at scale. Up to 10,000 recipients per day and 30 messages per minute per mailbox. Providers throttle bursts to fight spam, so pushing cold email through one mailbox hits limits and wrecks deliverability. High-volume outreach belongs on dedicated infrastructure that spreads sending across warmed inboxes — which is what Emailchaser does.
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