We are receiving this error when sending email to a domain: 554 Your access to this mail system from 220.127.116.11 has been rejected due to the sending MTA's poor reputation. If you believe that this failure is in error, please contact the intended recipient via alternate means.
I contact http://www.senderbase.org
support and they ask me to check this:
Your mail server is demonstrating suspicious behavior and we suggest that you investigate/fix the following:
* rDNS points to a fully qualified domain name (FQDN)
* rDNS points to a domain which matches the HELO FQDN
* rDNS points to a domain which matches the sender domain or a domain which matches the parent domain
To this end, one of the HELO string we are seeing "tssimx.com" which is not an exact match to the PTR of the IP 18.104.22.168 (mail.tssimx.com). This contravenes RFC2821, section 22.214.171.124 which states, "These [HELO] commands are used to identify the SMTP client to the SMTP server. The argument field contains the fully-qualified domain name of the SMTP client if one is available." I would suggest speaking with your provider about this if they are really using an improperly formatted HELO string.
Here are some helpful/informative links:
My server FQDN is exactly as in my dns host records.
I didn't find anything wrong on my DNS's . What exactly should i check? where is exactly "the HELO string we are seeing "tssimx.com""?
Thanks in advance