What does your email provider have to say about the problem?
According to your screenshot, - that rejection was done by “eig-east.smtp.a.cloudfilter.net”.
Note it says CloudFILTER, NOT CloudFLARE.
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Certain DNS records will NOT work with the Proxy status set to Proxied ().
The fifth A record, named mail" is for example one.
The third CNAME record, named “ftp” would be another one.
Various other DNS records, such as e.g. the ones named “cpcontacts”, “cpcaleneer”, “cpanel” and “webmail” may eventually cause some complications, if they’re set to Proxied ().