Why am I receiving an "unverified message" from a sender in my emails?

Emails are flagged as unverified when the email client like Outlook or Gmail cannot confirm the sender’s identity. 

There are a few reasons why this occurs, and it can be a sender related issue or security settings in your own email client.

Sender related issues

1. If the email is a promo or marketing newsletter it is likely being sent from an email marketing platform. There are email authentication protocols that help verify the sender’s domain.
The sender will need to resolve missing or incorrect SPF, DKIM, or DMARC records. If you are confident the sender is legitimate you can advise them of this issue so they can rectify. 

2. Issues with the sender’s email server, for example the sending email server maybe configured incorrectly or blacklisted, which can cause emails to be flagged.
In this situation you should flag the email as junk unless you are confident the sender is legitimate, in which case you can advise them of this issue so they can rectify. 

To flag the email as junk:
For Microsoft see: https://support.microsoft.com/...

Security settings in your own email client

Changes in your email client security settings such as updates may have tightened security measures, causing the email to be flagged.

If you are confident the sender is legitimate you can add them to your Safe Senders List:
For Microsoft see: https://support.microsoft.com/...