Hello M. E. Brannon
Thank you for reaching out to Microsoft Q&A Forum. I understand that you want to properly sync your email, contacts, and calendar across your desktop, laptop, and iPhone while using Outlook with an Office 365 Family plan and a local email provider.
Please make sure you already tried the Q&A Assist steps shared above. In addition, you can try the following steps:
1. Verify that the same email account is added to Outlook on all devices
Make sure the email address and account type match exactly on the desktop, laptop, and iPhone.
2. Check where contacts and calendars are stored in Outlook on Windows
Open Outlook and confirm whether contacts and calendars are associated with the email account or stored locally in an Outlook data file.
3. Ensure contact and calendar sync is enabled on iPhone
In the Outlook app settings, confirm that Contacts and Calendar sync are both turned on.
4. Avoid using POP if possible
If the account is set up as POP, consider switching to IMAP, as POP does not support full sync across devices.
5. Use Outlook on the web for verification
Sign in to Outlook on the web and check whether emails, contacts, and calendar items appear consistently there.
6. Rebuild the Outlook profile on one Windows device if sync inconsistencies persist
Remove the account from Outlook and add it again to refresh the synchronization state.
Please feel free to let me know how it goes after trying these steps. I truly appreciate your understanding.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.