nginx – How to stop OS/daemon information leakage in dovecot (server_tokens)?

How do I stop dovecot from telling its clients what flavour of linux I’m running and that it’s a dovecot imap server?

If I connect to my smtp server, I see the following snippet

user@host:~$ openssl s_client -crlf -connect mail.example.com:993
CONNECTED(00000003)
...
* OK (CAPABILITY IMAP4rev1 SASL-IR LOGIN-REFERRALS ID ENABLE IDLE LITERAL+ AUTH=PLAIN) Dovecot (Debian) ready.
...
user@host:~$ 

In nginx, you can set server_tokens off to disable such information leakage.

In apache, it’s

ServerTokens Prod
ServerSignature Off

What’s the equivalent setting to tell dovecot not to leak the OS or impa server I’m running to clients?