Microsoft 365 4.7.850-899
Access denied, please try again later
Microsoft 365 4.7.850-899 means: access denied, please try again later. It is a temporary failure, so your server retries it. Stop sending from the affected account or IP until the cause is fixed. Check for a compromised account, and remove unverified and unengaged addresses before you resume.
Microsoft 365’s exact wording
Quoted from Microsoft Learn: Email non-delivery reports and SMTP errors in Exchange Online, checked 2026-11-05. Placeholders are Microsoft 365’s own.
Provider's description
Access denied, please try again later
Possible cause
Suspicious activity was detected on the IP in question, and the address is temporarily restricted while being further evaluated.
Provider's advice
If this activity is valid, this restriction is lifted shortly.
| Who sends it | Microsoft 365, Exchange Online and Outlook.com |
|---|---|
| Basic code | Microsoft 365 lists the enhanced code only |
| Enhanced code | 4.7.850: Microsoft 365-specific, not in the IANA registry. Its subject digit puts it under 5.7.0 other or undefined security status. |
| Permanent or temporary | Temporary (4xx) |
| Verifying the list prevents it | Partly |
What the sender should do
Stop sending from the affected account or IP until the cause is fixed. Check for a compromised account, and remove unverified and unengaged addresses before you resume.
Would verifying the list have prevented Microsoft 365 4.7.850-899?
Partly
The reply is not only about one address, but providers weigh how often a sender hits addresses that do not exist. Removing bad addresses before sending lowers that signal.
Common questions
- What does Microsoft 365 4.7.850-899 mean?
- Microsoft 365 4.7.850-899 means: access denied, please try again later. It is a temporary failure, so your server retries it. Stop sending from the affected account or IP until the cause is fixed. Check for a compromised account, and remove unverified and unengaged addresses before you resume.
- Should I retry after Microsoft 365 4.7.850-899?
- Your sending server retries it automatically, because it is a temporary (4xx) failure. Investigate only if it keeps coming back over several hours.
- Would verifying my list have prevented Microsoft 365 4.7.850-899?
- Partly. The reply is not only about one address, but providers weigh how often a sender hits addresses that do not exist. Removing bad addresses before sending lowers that signal.
Sources
- Microsoft Learn: Email non-delivery reports and SMTP errors in Exchange Online (checked 2026-11-05)
Registry and provider wording is quoted exactly; guidance is written by the SimpleVerifier Team.
SimpleVerifier Team · Last checked against the sources 2026-11-05