Send mail failed help me

Send Mail failed:
[I ask for help, for a couple of days when I send emails from my wix mail control panel, it tells me that the email is sent but they don’t actually receive my email. I did various tests, when receiving I noticed that I can receive emails but not when sending. What could it be and where to intervene?
I would like to point out that the site is pointed to with DNS from another provider but everything has always worked, I am losing money due to not being able to contact customer requests.
Thanks if you help me.]

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