error 500 on some mail account with roundcube

[damiano1984]

Hi guys,
i have a problem with some mail accounts; when i try to open them webmail gave me error 500, the other works fine.
I can open every account and the main cpanel account with horde.
I have tryed to modify tweak setting on whm without resoult.
My whm version is 90.0.16 ( stable )
Have anyone any suggestion?

Thank you very much
Damiano

p.s. excuse me for my bad english