kmail repeats messages continuously.
Help me please!

https://ibb.co/kBKtm5
https://ibb.co/nBwCeQ
https://ibb.co/cnskzQ

What can I do?

You would need to enable html in kmail. Personally I wouldn't, though.

Still the same...
Thank you!

Do you need more information on the kmail configuration?

Hm, it looks like an upstream issue. Which distro and version of Kmail are you using?

Here some more info https://bbs.archlinux.org/viewtopic.php?id=221050

Gentoo
kernel 4.12.5
kmail 5.5.3

Any other Gentoo users with the same problem?

Or do we have other kmail 5.5.3 users with the same problem on here?

I'd suggest reading through the ArchLinux thread and follow their procedure.