old email is lost somewhere, how can I retrieve it?

The corrected rule will handle new messages, but it will not automatically recover or process messages from Wednesday through Sunday; first locate those messages, then run the rule manually against the folder containing them.

1. Determine whether the messages reached the mailbox

Sign in through a browser:

• For a personal Microsoft account, use Outlook.com.
• For a work or school account, use your organization’s Outlook on the web.
• For another provider, use that provider’s webmail.

Search All folders for a known sender, subject, or phrase from the affected period. Also inspect Inbox, Archive, Junk Email, Deleted Items, and any folder used by the previous rule.

If the messages are found in a folder:

1. In classic Outlook, select that folder.
2. Go to File → Manage Rules & Alerts → Run Rules Now.
3. Select the corrected rule.
4. Under Run in Folder, choose the folder where the messages were found.
5. Optionally select Include subfolders, then choose Run Now. Classic Outlook supports manually applying rules to messages already present in a folder.^1^

2. If they appear online but not in classic Outlook

For supported cached or synchronized account types:

1. Go to File → Account Settings → Account Settings.
2. On the Email tab, select the account and choose Change.
3. Move Download email for the past to All.
4. Select Next → Done, restart Outlook, and allow synchronization to finish.

If that slider is unavailable, skip this step. Microsoft documents it as the way to download more historical mail into classic Outlook’s local cache.^2^

If the messages are downloaded but search still misses them:

1. Select the Outlook search box.
2. Choose Search Tools → Indexing Status.
3. Wait until no items remain to be indexed.
4. Under Search Tools → Locations to Search, ensure the relevant mailbox or data file is selected.^2^

Only if synchronization remains broken should the account be removed and added again. Before doing that, preserve any local .pst files and rule out POP/local-only mail, because removing an account does not restore data that exists only on a device.^3^

3. If the messages are absent from webmail

Check Deleted Items first. Select the messages, then use Home → Move to return them to the Inbox or another folder.

If they are not there:

1. Select Deleted Items.
2. On the Home tab, select Recover Deleted Items From Server.
3. Sort by Deleted On, From, or Subject.
4. Select the affected messages.
5. Choose Restore Selected Items → OK.
6. Restored messages return to Deleted Items; move them from there to the desired folder.

If Recover Deleted Items From Server is absent, that account does not support this recovery method. Recovery is also time-limited by the mailbox’s retention policy.^4^

4. Check for POP downloads or local archives

If this is an Outlook.com account, check Settings → Mail → Forwarding and IMAP. If POP is enabled, inspect every older computer, phone, and mail program that accessed this account: a POP client may have downloaded the messages and removed them from the server. Do this before changing the POP configuration.^3^

Also check existing Outlook archives:

1. In classic Outlook, select File → Open & Export → Open Outlook Data File.
2. Open any known .pst archive or backup.
3. Search its folders for the missing date range.^3^

5. Escalate if no copy can be found

• Personal Outlook.com account: select Help → Help → Still need help? to contact Outlook.com support.
• Work or school account: contact the Microsoft 365 administrator. The administrator can check retention and recovery options and, if necessary, open a Microsoft support request.^5^

If the mailbox, recoverable items, local devices, and archives contain no copy, support or the administrator must determine whether the messages were accepted by the mailbox and whether any server-side recovery remains available.

References

1. New Outlook
2. Classic Outlook
3. Emails in my inbox prior to Sunday 11th October have disappeared. - Microsoft Q&A
4. Classic Outlook
5. Older emails past 2 days are missing from my inbox in Outlook. Need to restore them. - Microsoft Q&A