Hello,
I am writting as Linakis Digital company's System Administrator.
We have a mail server which cannot send mails to some domains (vodafone.com / minerva.com.gr) which use as SMTP cluster5.eu.messagelabs.com & cluster3.eu.messagelabs.com.
Below is telnet outcome from this server.
C:\>telnet cluster5.eu.messagelabs.com 25
Connecting To cluster5.eu.messagelabs.com...Could not open connection to the host, on port 25: Connect failed
C:\>telnet cluster3.eu.messagelabs.com 25
Connecting To cluster3.eu.messagelabs.com...Could not open connection to the host, on port 25: Connect failed
Note that from our other Mail server we can send emails and we can telnet on port 25.
We also tried blacklist tool http://ipremoval.sms.symantec.com/lookup/ and we got response " The IP address you submitted, X.X.X.X, does not have a negative reputation and therefore cannot be submitted for investigation."
Please advice and also inform us if there is a way to send you the Mail Server IP on some private message to further investigate.
Regards,
Kyriakos Tzanoulinos