Outlook is deleting some emails are they are received. Afther that I am unable to locate the email

Dear @JMuncy,

Welcome to Microsoft Q&A Forum! 

Based on your description, this behavior of your Outlook may be from setting rules, spam/quarantine actions, or a retention policy. Therefore, if your Outlook account is personal account, please kindly see this article and try it first: Email is missing from your Outlook.com inbox - Microsoft Support 

In case that your Outlook account is business account (work or school account), then I find several suggestions that may help you, please consider trying them: 

1.If you're managing their email domain (e.g., via Microsoft 365 or another provider), check the message trace or email logs to see whether the service delivered, quarantined, or deleted each message and which policy/rule acted. (Note: this feature needs Administrator right to use it. If you do not have the right, please kindly contact the IT Admin in your organization to search it for you)

References: Run a message trace and view the results in the Exchange admin center in Exchange Online | Microsof… 

2.You should check Blocked Senders or Safe Senders because sometimes senders are unintentionally blocked:  

• Go to Settings > Mail > Junk email in Outlook.  
• Check Blocked senders and Safe senders lists.  

Please see more details in here: Block or unblock senders in Outlook - Microsoft Support 

3.You should check the quarantine portal or security dashboard because even if spam/junk folders were checked, some emails might be quarantined by Microsoft Defender for Office 365. 

You can consult in here: Find and release quarantined messages as a user - Microsoft Defender for Office 365 | Microsoft Lea… 

4.You may check again for the Transport rules in Microsoft 365 Exchange Admin Center. Mail flow rules that might redirect or delete emails. Also, check the Inbox Rules in Outlook, please click Settings icon > Mail > Rules to see if there are any rules may cause this issue. Reference: Manage email messages by using rules in Outlook - Microsoft Support

5.I found that Outlook has Sweep feature that may cause this issue, so you should clarify it as well, please see this: Organize your inbox with Archive, Sweep, and other tools in Outlook on the web - Microsoft Support 

If the messages are found in Deleted Items or Recoverable Items, you can follow this article: Recover and restore deleted items in Outlook - Microsoft Support to get it back. 

I hope this information can help you in this case and please feel free to let me know your update in comment section. Wish you a pleasant day! 

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