Emails are not sending from logged in user salesforce

In Salesforce lightning when we log in as another user from the system admin or any other profile which has Log In As Another User permission, sometimes emails are not triggered to the recipients. 

Let us see an example.

User1 with admin profile is logged into the Salesforce, navigates to user2 record from the setup. Clicks the Login button in the User2 record page, which takes User1 into the User2 account from which emails are not getting triggered.  

One of the reasons is the email verification of the user2 account. Yes, most of the time when we create the test user in Salesforce, we do not perform account verification as we log in to these test accounts directly from the system admin instance.

Have a look at the highlighted consideration below from the Salesforce documentation

To resolve this, either verify the user account by clicking the verification link received in the registered email or create a new user, verify the email account, and log in as another user from the admin profile. 

That's it! Emails will get triggered out with their respective functionalities without any issues. 

In addition to the above-mentioned scenario, email triggering in Salesforce depends on several other factors. If your issue still exists, check out troubleshooting delivery problems for Salesforce emails. 

If you have resolved this issue with any other workaround, please share it in the comments section below.

Until then...

Reference

Salesforce documentation