Hello,
thank you for your reply.
I'd like to provide 2 quick additional details before trying your suggestions:
1) If I add a from address at the command line, then mail is delivered ok:
$ mail Alеxander.Farber@gmail.com -r wеbmaster@prеferans.de
But if I just run
$ mail Аlеxander.Farber@gmail.com
then it is rejected by Gmail.
So I could append "| mail -r wеbmaster@preferans.de" to all my cronjobs, but I'm looking for better solution
2) My ISP (hetzner.de) doesn't provide mail relaying at all.
Regards Alex