Hello Erica K5,
Thank you for posting in Microsoft Community. I'm happy assisting you with this request.
Based on your description I understand that you have a trouble in setup your account in Office 365. Kindly if you can clarify more details about the trouble like screenshot or error code, that would be better. Anyway, please checkout the following steps..
Setup your account:
-Click on File and select Account Settings.
-Click New to create a new email setup.
-Choose Manual setup or additional server types, then select Next.
-Configure IMAP Settings:
-Select IMAP as the account type.
Fill in the following details:
-Your Name: Enter your name.
-Email Address: Your Telstra email address.
-Logon Information:
-Username: Your Telstra email address.
-Password: Your Telstra email password.
-Untick the box for Log on using Secure Password Authentication (SPA).
Server Information:
-Account Type: IMAP.
-Incoming Mail Server (IMAP): imap.telstra.com.
-Outgoing Mail Server (SMTP): smtp.telstra.com.
-Mail to keep offline: User-defined (all by default).
Advanced Settings:
-Click More Settings.
-Go to the Outgoing Server tab.
-Tick the box for My outgoing server (SMTP) requires authentication.
-Under Server Port Numbers:
-Incoming server (IMAP): 993.
-Choose SSL for the encrypted connection.
-Outgoing server (SMTP): 465.
-Again, choose SSL for the encrypted connection.
-Click OK and then Next.
Test Your Settings:
-Outlook will test your email settings.
-Once it’s done, select Close.
-Finally, click Finish.
I look forward to your response,
Best regards,
Community Moderator