Sending email from AS400 is successful but user is not receiving the email

[JustinWithoutAnE]

I'm trying to send an email to a user to a user that has an email address ending with a country code(example: receiver@company.com.pl). I use SNDSMTPEMM to send the message. the job log says the message is successfully sent but according to the network guys no emails from the AS400 is being sent to the user.
When I try to send to my email(Example: support@company.com) I receive it just fine.

Any suggestions or ideas?