Outlook.com cannot completely reject spam before it reaches a personal mailbox; since Strict is already enabled, use domain/pattern rules for messages still reaching the Inbox, and treat messages already in Junk as successfully filtered.
If the spam is reaching your Inbox
- Block recurring domains rather than individual addresses
- Open Outlook.com.
- Go to Settings → Mail → Junk email.
- Under Blocked senders and domains, select Add blocked sender.
- Enter the part after
@, such as spamdomain.example, and save.
Blocking moves future messages to Junk; it does not prevent delivery to the mailbox. Domain blocking is useful only when the same domains recur—avoid blocking major shared domains that legitimate senders use. ^1^
- Create rules for stable characteristics shared by the duplicates
- Go to Settings → Mail → Rules → Add new rule.
- Give the rule a name.
- Add a narrow condition such as:
- Subject includes a repeated phrase;
- From a recurring sender or domain; or
- another characteristic consistently present in the spam.
- Set the action to Delete or move the message to a separate folder.
- Add exceptions for legitimate messages where necessary.
- Enable Stop processing more rules, then save.
Rules apply to incoming mail. Keep conditions specific because a broad keyword rule can delete legitimate messages too. ^2^
- Report phishing instead of merely deleting it
- Select one or more messages.
- Choose Report → Report phishing.
Reporting sends information to Microsoft, but it does not itself block subsequent messages from that sender. ^3^
If the messages are already in Junk
That means Strict filtering is containing them. Outlook.com’s Block feature also sends blocked mail to Junk rather than refusing it, so repeatedly blocking rotating addresses will not stop the Junk folder from filling. ^4^
Practical options are:
- Select Junk Email → Delete all periodically. ^1^
- Continue reporting representative messages as junk or phishing; there is no need to report hundreds of identical copies individually.
- Review Junk regularly because restrictive filtering can also classify legitimate mail as junk.
- Do not unsubscribe from obvious spam, open attachments, or follow its links; doing so can confirm that the address is active.
Escalate the unexplained volume
Because this has continued at roughly 300 messages per day for several months despite Strict filtering, report it to Outlook.com Support:
- While signed in to Outlook.com, select Help at the top.
- Search for the issue.
- If the suggested answers do not resolve it, scroll to Still need help? and select Yes.
- State that Strict filtering is already enabled, include the approximate daily count and duration, and clarify whether the messages land in Inbox or Junk. ^5^
If there are also password-change notices, unfamiliar sent messages, or unknown sign-in activity, treat that separately as possible account compromise and review the account’s recent activity and security information. A spam surge by itself does not establish that the account was hacked. ^6^
References
- Filter junk email and spam in Outlook
- Manage email messages by using rules in Outlook
- Phishing and suspicious behavior in Outlook | Microsoft Support
- Fixes or workarounds for recent issues on Outlook.com | Microsoft Support
- How to get support for Outlook.com
- Help protect your Outlook.com email account | Microsoft Support