My IP address is blocked by AT&T
I have a mail server with a static IP that receives "5.3.0 flph834 DNSBL:ATTRBL 521< IP_x.x.x.x >_is_blocked. For assistance forward this error to email@example.com" error message when sending email addresses.
Is there an alternative method to contact the abuse support besides the firstname.lastname@example.org email ? I have send the email to that address and received no response. Could you please advice me, thanks in advance.