Possibly grist https://www.getgrist.com/blog/grist-v-airtable/ ?

FYI, Grist has a very good Airtable migration tool. Brings over column types, references, simple formulas, attachments etc: https://www.getgrist.com/airtable-alternative-self-hosted/

Check out Bluetivity. Tons of functionality and easy to use.

Baserow

Unfortunately it seems it not supporting email sending out of the box

It depends what you need, there are many options these days. https://chatgpt.com/?hints=search&q=Any%20suggestion%20to%20...?