some of my emails are not sending and i need help

Hi @Trish Morrissey,

Just to gently clarify before going any further, you are posting in the Microsoft Q&A community forum, which is a user-to-user support forum and is separate from Microsoft Support. Community members do not have access to your tenant, account permissions, or Microsoft's internal systems, so I can only do my best to assist within the scope of this forum and help guide you to the appropriate support team when necessary.

The error 550 5.7.23 normally points to an SPF validation problem. administrator should check the full diagnostic details in the rejected message and verify the SPF DNS record for your sending domain. If you are the only administrator and have lost access to the tenant, resolving the SPF issue yourself may not be possible until administrator access has first been restored.

The best next step is to contact Microsoft Support by phone so that the frontline support team can create a support case and route it to the Data Protection Team. You can find the appropriate phone number for your region here: Contact Microsoft customer support.

In this situation, the Microsoft Data Protection team has tools and processes in place to verify identity and regain access to administrator accounts.   

Here are some tips and an example of a prompt to help you navigate the IVR more effectively:   

(When you call the support number, you may hear an introduction of about 30 seconds such as "you can visit the link...". You can ignore this introduction and wait until you are presented with the options. Then press "1" as a business email user, and again "1" for technical help.)     

In some regions, the initial interaction may be automated, so here’s a general idea of how the conversation might go to help you prepare:       

What kind of problem are you experiencing?          

Answer: Authenticator          

What products do you use?          

Answer: Office 365 for business          

Is this for an education or company account?          

Answer: For companies          

Are you an administrator?          

Answer: Yes          

Are there any other administrators in your organization?          

Answer: No. I am the only admin in my tenant           

Do you need a... Service request?           

Answer: Yes. I need to create a ticket. Please send me direct to the Data Protection Teams.       

During the phone call, you will need to provide the information associated with your subscription, such as your company name, billing details, phone number, and an alternate email address, etc. This information allows the Data Protection team to verify your identity and securely assist you in regaining access to your administrator account.     

Once administrator access has been restored, you can review the guidance in Fix NDR error 5.7.23 in Exchange Online to troubleshoot and correct the SPF-related issue.

If additional assistance is needed, you can also open a support ticket with Microsoft. At that stage, a Microsoft Support engineer will be able to work with you directly to further investigate the mail flow issue, review your SPF configuration, and help identify the cause of the delivery failures.

Thank you for your understanding and your time.