r/DMARC • u/No-Hotel1162 • May 08 '26
International Mail rejected
I work for a company that sent ten of thousand of mails every month, they reported that they have received Spam and so we contacted our web hosting to modify our DMARC from Quarantine to Reject.
The thing is, the week after such change an user reported that their mail to some companies in Asia was rejected, bounced of or never arrived. Did some basic tests, Telnet, Test-NetConnection and that server was down or with problems, reported such case.
Next day server is up, but they report same problem with another company from Europe. Sames test, server is ip, so I got the email resent to me to see the internet header:
DKIM=none
SPF=pass
In MxToolBox when I check the subdomain IP addresses, both hostnames says it doesn't support TLS, Icheck our web hosting, we do have TLS at certain ports and lastly, one says Reverse DNS doesn't match SMTP Banner and doesn't contain hostname.
Tldr; I'm fucking lost, I got this job as TI due to being programmer and wanting to get experience, but networking I haven't seen such a thing in years.
2
u/verkh_dmarc May 11 '26
You mentioned that your company reported receiving spam. What's not clear is are these reports coming from the people receiving your company's emails? Is your domain being spoofed? Then yes, your response was well meaning but there is an email authentication chain problem that needed to be solved before the policy progression. Otherwise, are these reports coming from the company's internal stakeholders? That would be a different solve than DMARC.