Hi,
Thank you for writing to Microsoft Community Forums.
In order to get clarity and to assist you accordingly, please reply with the answers to the questions below:
- What is the Version and Build of Windows 10 installed on the PC? (Type winver in Windows search/Run command)
- What is the Version of Mail app installed?
- Are you aware of any changes prior to this issue?
In this scenario, we would suggest you to configure mail app as mentioned in below steps:
1. Open Mail app and click on the gear icon to open Settings.
2. Click on Manage accounts, click on + Add account
3. Scroll and select Advanced setup.
4. Select Internet Email and then add all the details required
5. Change the name under Send your messages using this name to the correct account holder.
Let us know the results. If the issue persists, we will certainly assist you further.
Aditya Roy
Microsoft Community – Moderator