error Class "Martin\Forms\Classes\Mails\Notification" does not exist

[RenderWarrior]

Hello,

I'm moving a site made with WinterCMS on my server.
It loads, and I configured the SMTP params.
When I try to send an email from a form made with Magic Forms, I get this error:
Class "Martin\Forms\Classes\Mails\Notification" does not exist

I'm new to WinterCMS and to Laravel, so I'm not sure where to check.

Could you help me, please?

Thanks a lot!

Best regards