Hi zotov
How do you send your e-mails? Are you using a mailclient (f.e. MS Outlook, MacMail etc) or the bluewin webmail?
Please try to send an email to your own address to check how your mailaddress is shown.
Perhaps you have some wrong credentials in your mailaccount settings.
If you need assistance for setting up your mailaddress in a mailclient, we recommend you the My Swisscom Assistant: click here
Kind regards