GMAIL + Undelivered Mail Returned to Sender

Dobrý den, mám problém s příchozí poštou na gmailu, kterou používáme jako alias, která se tváří takto:

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This is the mail system at host wes1-so1-redir.wedos.net.

I’m sorry to have to inform you that your message could not
be delivered to one or more recipients. It’s attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The mail system

<****@gmail.com>: host gmail-smtp-in.l.google.com[142.250.27.27]
said: 550-5.7.26 This message does not pass authentication checks (SPF and
DKIM both 550-5.7.26 do not pass). SPF check for [bluewagon.cz] does not
pass with ip: 550-5.7.26 [46.28.105.100].To best protect our users from
spam, the message has 550-5.7.26 been blocked. Please visit 550-5.7.26
https://support.google.com/mail/answer/81126#authentication for more 550
5.7.26 information. sb1-20020a1709076d8100b007af0bc6e10asi16235462ejc.213 –
gsmtp (in reply to end of DATA command)

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Někdy je dole připojená i původní zpráva od odesílatele, někdy ne.

Děkuji za pomoc.

DM