nanog mailing list archives

Re: Charter and Cox contacts


From: Mark Milhollan <mlm () pixelgate net>
Date: Tue, 14 May 2019 11:22:41 -0700 (PDT)

On Mon, 13 May 2019, Stephen Satchell wrote:
On 5/13/19 12:11 PM, daniel () pyranah com wrote:

Does anyone have contacts at Charter (Spectrum) and Cox? For some reason,
our IP has been blocked by them and our customers are unable to send email
via their charter/cox accounts. Thanks

Would you be talking about port 25/tcp outbound?  Lots of ISPs will
block port 25 as a rule;

If this is the case, that your customers cannot use your mail servers to relay mail then provide port 587/TCP (SUBMISSION) or even 465/TCP (SMTPS, deprecated).

If you mean that your mail servers can't send mail to Charter and Cox addresses, then indeed you need to find out what happened, fix it then request removal from their (and other) blacklists for which contacts there would be helpful (I am not one).


/mark


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