Permanent failure — do not retry
SMTP 550 5.7.705
tenant has exceeded threshold (Microsoft 365)
SMTP 550 5.7.705 means Microsoft has blocked outbound mail from your whole Microsoft 365 tenant. The text reads "Access denied, tenant has exceeded threshold." Microsoft says this happens when a tenant sends too much spam, usually because a server or admin account was compromised.
How it appears
550 5.7.705 Access denied, tenant has exceeded threshold.
What causes it
- A compromised account or on-premises server sent spam through the tenant.
- Bulk or cold mail was sent through ordinary Microsoft 365 mailboxes.
- Microsoft also lists a lapsed subscription as a possible cause.
How to fix it
In order — try the first one first.
- Find and secure the compromised account or server first.
- Remove any rogue connectors or forwarding rules.
- Contact Microsoft Support to have the tenant unblocked once it is clean.
- Move bulk sending to a dedicated sending service.
Common questions
- What does SMTP 550 5.7.705 mean?
- SMTP 550 5.7.705 means Microsoft has blocked outbound mail from your whole Microsoft 365 tenant. The text reads "Access denied, tenant has exceeded threshold." Microsoft says this happens when a tenant sends too much spam, usually because a server or admin account was compromised.
- Should I retry a 550 5.7.705 error?
- No. 550 is a permanent failure, so the message will never be delivered no matter how many times you try. Remove the address — repeated sends to permanent failures are one of the main signals mailbox providers use to throttle a sender.
- How do I fix SMTP 550 5.7.705?
- Find and secure the compromised account or server first.
Other 550 replies
- 550 5.1.1 — mailbox does not exist
- 550 5.7.1 — message refused by policy
- 550 5.4.1 — recipient address rejected, access denied
- 550 5.2.1 — mailbox disabled, not accepting messages
- 550 — mailbox unavailable
- 550 5.1.0 — address rejected, other address status
- 550 5.1.10 — recipient not found (Microsoft 365)
- 550 5.1.8 — bad outbound sender (Microsoft 365)
- 550 5.4.5 — daily sending limit exceeded (Gmail)
- 550 4.4.7 — message expired in the queue
- 550 5.7.25 — no PTR record for sending IP (Gmail)
- 550 5.7.26 — blocked, sender unauthenticated (Gmail)
- 550 5.7.27 — SPF authentication failed (Gmail)
- 550 5.7.28 — unusual rate of unsolicited mail (Gmail)
- 550 5.7.23 — SPF violation (Microsoft 365)
- 550 5.7.124 — sender not in allowed senders list (Microsoft 365)
- 550 5.7.509 — DMARC failed, policy reject (Microsoft 365)
- 550 5.7.606-649 — banned sending IP (Microsoft)
- 550 5.7.708 — traffic not accepted from this IP (Microsoft 365)
- 550 5.7.750 — blocked from sending from unregistered domains (Microsoft 365)
- 550 5.7.515 — authentication required for high-volume senders (Outlook.com)
- 550 5.7.1 S3140 — IP range on Outlook.com block list
Last reviewed 2026-09-11