Hello,
By "Outlook", do you mean Outlook desktop application or Outlook.com webmail interface? From the description, it looks are you using the Outlook.com webmail interface, correct?
>>the other times it wasn't a valid email address or it was being sent from myself.
If you cannot add a junk email address to the blocked sender list because the email address is invalid, this is the expected behavior. Only properly formatted SMTP addresses or domains can be added to the Block Sender List. As a workaround, we may consider
to create an Outlook rule to delete these junk emails or move them to the Junk email folder.
Meanwhile, I'd recommend you have a look at the following article on some tips to keep spam out of your Inbox in Outlook.com:
https://support.office.com/en-us/article/Help-keep-spam-out-of-your-Inbox-in-Outlook-com-a3ece97b-82f8-4a5e-9ac3-e92fa6427ae4
Since this forum is for general questions and feedback related to Outlook desktop application, if your question is related to Outlook.com, I'd recommend you post a new question to the forum dedicated to Outlook.com:
https://answers.microsoft.com/en-us/outlook_com/forum
The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction with us.
If I've misunderstood something, please feel free to let me know. Thank you for your understanding.
Regards,
Steve Fan
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