1 answer
HI,
Do this setting:
1. Setup > Search for Email-to Case (Feature Settings > Service > Email-to case > Click on this > Edit the Email-to case setting > Enable Email-to case (first one) and save it
2. Go to Set up > Object Manager > Case > Page layout > Case layout (the layout where you want to display) > Edit > click on override the predefined actions > Make sure Email Action added > Save
refer:
https://probablesolution.blogspot.com/2021/11/email-tab-not-visible-in-feed.html