Check the following list of items to troubleshoot and fix your sending and receiving emails issue:

1. Check your internet connection.
2. Check for any changes to the server configuration.
3. Verify username and password for your mail account.
4. Check if your email client is correctly configured.
5. Check for any browser or firewall settings that can interfere with emails.
6. Try using a different device to see if something is wrong with your original computer.