Double e-mal notices

Why does suite sends double e-mail notifications to a contact when the case is being created. First notice is correct according to a template but then comes second one without subject and body text. I checked workflows - there are not a single one and email template regarding case creation is only one.

P.S. I have also tried to delete all email templates but even when there’s no templates - empty e-mail notifications comes to contact after import. Could anyone advise something what could be wrong or what causes these double notifications?

Thanks!