Hi @Mary C ,
How can I prevent unauthorized access to my email address?
You can check your sign-in location information by going to your your Microsoft account's security options and selecting Review activity.
To prevent your account from being hacked in the future, see Help protect your Outlook.com email account.
And I have found a similar thread which mentioned that you can ask your friends to block the real senders email address.: https://answers.microsoft.com/en-us/outlook_com/forum/all/friends-getting-spam-email-from-me/01c456b2-e412-49fc-9cd7-a404959d3055
Please kindly understand here which mainly focus on general issues about Outlook desktop client. So, in order to better solve your issue, it is suggested for you to post a new thread to the dedicated forum for more appropriate help via this link.
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