This can go into three scenarios:
If attacker has already compromised your emailid/password,then he/she can login from browser to gmail.com or outlook.com , then only login activity provided by your email vendor is helpful. Gmail, usually asks for OTP on your device if it suspects that you are trying to login from a suspect location(ex. moscow).
If you are using an email client like outlook/thunderbird, then attacker can read the email(s) and destroy evidence of it as well.
Attacker might have set up a forwarding email address in your account by which he/she can get access to all the emails being sent currently.
WHAT WOULD I DO IF I WERE YOU:
1) Change the password from a fresh device and signout of all devices (still not reliable the attacker can be controlling your PC and can log all your activity)
2) Ask my friend to send an email like to my emailID
Hey Ashutosh,
Can you let me know the account number / wallet ID in which i can transfer you the remaining ammount?
Regards,
Bob
If the attacker is not so smart , he/she can get honeytrapped.
Some email provider has 2-step verification which may help avoid someone else accessing your account. What's more, please change your password immediately. – Perry – 2019-05-08T05:58:02.893