avoid external emails that the from=< and the to=< are the same user

[Francesc Peñalvez]

Lately we are receiving spam mails that apparently the mail from the and the to is the same. How is it possible to avoid this?. I have configured postfix to avoid the relay of emails and to be able to send mail through my postfix is necessary the auth , these emails are sent externally from several ips and seeing the logs of those emails are not authenticated

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If you have received this message in error, please notify immediately the 
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smime.p7s
Description: Firma criptográfica S/MIME