[Users] How to prevent IMAP NOOP?

[Removed GDPR]

I noticed in the network log that every minute Claws sends a NOOP:

[10:55:34] IMAP> 720 NOOP
[10:55:34] IMAP< 720 OK Success
[10:56:34] IMAP> 721 NOOP
[10:56:34] IMAP< 721 OK Success
[10:57:34] IMAP> 722 NOOP
[10:57:34] IMAP< 722 OK Success
...

I don't want the server to know that I am online and that my mail
client is running. I want to check my email manually only and not
notify anyone what I am doing meanwhile.

So how can I prevent this NOOP sequence?