Open source software for emails, something like thunderbird

Hello, please help me with some information, I want an open source software for emails, something like thunderbird, but which also has the following functionalities:
- tracking on emails, if the email was read,
- several filters, for example to be a filter that shows me the emails to which the customers did not respond in the last week
- to be able to schedule the sending of emails
- to be able to send emails to a group of emails

Thanks.

These might be worth looking into. Research on these and see for yourself which one caters to your requirements in the best way possible.
1. Mailbird
2. Postbox
3. eM Client
4. Spark
5. Airmail

i use spark, really good one

Top 10 Email Software

• Outlook.
• Google Workspace.
• Zoho Mail.
• Front.
• Titan.
• Protonmail.
• Microsoft Exchange Online.
• Microsoft Exchange Server 2019