Email Security.cloud

Hello.
I am the administrator of the mail server windows-plesk.comel-it.com
Recently, one of our clients reported that they could not send messages to messagelabs.com customers.
Our server obtains the message as in the post title. The IP of our server is 78.28.40.175 and we are not listed on any blacklist.
Please tell us what steps we have to make to make the small pass properly.

Hi Witold,

I have now reset the confidence of this IP 78.28.40.175 across all our infrastructure, as the confidence was low and we were blocking your connections.

This will fix the issue and you will no longer get issues sending emails from that IP to our customers.

Please can you set this thread as resolved to prevent other people adding to it.

Kind regards

Kevin Brosnan

Tier 2 Senior Technical Support Engineer

Thank you for your answer.
Unfortunately, messages sent from our server to the service that your service uses do not reach the intended recipient. Can we still do something about it?
Below log from our system.

Fork/Split: Message ID [263828E59D424DCAB24A50EC1ABD5CE8.MAI] requeued/split into 1 messages for delivery to target domains.
 Queued: Message ID [263828E59D424DCAB24A50EC1ABD5CE8.MAI] queued for delivery to the domain [******.as] at the SMTP Outbound Queue with a new Message ID of [263828E59D424DCAB24A50EC1ABD5CE8.MAI]

Status: SMTP Outbound Delivery details for Message ID [263828E59D424DCAB24A50EC1ABD5CE8.MAI] to domain [******.as] follow below: 
06/29/17 08:15:57    SMTP-OU    263828E59D424DCAB24A50EC1ABD5CE8.MAI    2424    216.82.251.230    CONN        220 server-13.tower-555.messagelabs.com ESMTP    0    47    ******    ******
06/29/17 08:15:57    SMTP-OU    263828E59D424DCAB24A50EC1ABD5CE8.MAI    2424    216.82.251.230    EHLO    EHLO poczta.comel-it.com    250-server-13.tower-555.messagelabs.com says EHLO to 78.28.40.175:64979    26    117    ******    ******
06/29/17 08:15:58    SMTP-OU    263828E59D424DCAB24A50EC1ABD5CE8.MAI    2424    216.82.251.230    EHLO    STARTTLS    220 2.0.0 continue    10    20    ******    ******
06/29/17 08:15:59    SMTP-OU    263828E59D424DCAB24A50EC1ABD5CE8.MAI    2424    216.82.251.230    EHLO    EHLO poczta.comel-it.com    250-server-13.tower-555.messagelabs.com says EHLO to 78.28.40.175:64979    26    103    ******    ******
06/29/17 08:15:59    SMTP-OU    263828E59D424DCAB24A50EC1ABD5CE8.MAI    2424    216.82.251.230    MAIL    MAIL FROM:<******@******.biz>    250 2.0.0 MAIL FROM accepted    33    30    ******    ******
06/29/17 08:15:59    SMTP-OU    263828E59D424DCAB24A50EC1ABD5CE8.MAI    2424    216.82.251.230    RCPT    RCPT TO:<******@******.as>    421 Service Temporarily Unavailable    30    37    ******    ******
06/29/17 08:15:59    SMTP-OU    263828E59D424DCAB24A50EC1ABD5CE8.MAI    2424    216.82.251.230    QUIT    QUIT    -    6    0    ******    ******

Debug delivery information for Message ID [263828E59D424DCAB24A50EC1ABD5CE8.MAI] 
06/29/17 08:15:57    ME-I0018: [49BD3348DD474CC6AEF7F7E15F157CD1.MAI] Outbound message from ([SMTP:******@******.biz]) requeued as [263828E59D424DCAB24A50EC1ABD5CE8.MAI] to the target domain [******.as]
06/29/17 08:15:57    ME-I0026: [263828E59D424DCAB24A50EC1ABD5CE8.MAI] Sending message
06/29/17 08:15:57    ME-IXXXX: [263828E59D424DCAB24A50EC1ABD5CE8.MAI] DNS resolved to the following record: IP Address=216.82.251.230, Family=2, Type=1, Protocol=6
06/29/17 08:15:59    ME-E0034: [263828E59D424DCAB24A50EC1ABD5CE8.MAI] RCPT commands were returned with a 421 response, meaning that the entire message should be retried.
06/29/17 08:15:59    ME-I0009: [263828E59D424DCAB24A50EC1ABD5CE8.MAI] Remote server has closed connection (error 6001) after 0 milliseconds. Server Response: (-)
06/29/17 08:15:59    ME-E0059: [263828E59D424DCAB24A50EC1ABD5CE8.MAI] Message Delivery Failure. Attempt (1): Domain (******.as) returned temporary error for email. Message has been requeued.

Hi Witold,

Could you provide the sender and recipients full email address, I will need to investigate further on this.

Kind regards

Kevin Brosnan

Hi.

The Sender is: matthias@stakom.biz

recipient: henning@nordcon.as

Kind regards Witold Konieczny

Hi Witold,

I have looked into this issue and found that the problem is with neither you or Symantec. The recipient domain have their MX records configured incorrectly. I am trying to contact someone associated with their company to inform them of this. However, to speed things up you may wish to contact them directly (if you have a contact) to inform them to look into this and contact our support team if needed.

I am unable to to give you any other information other that for security reasons.

Please let me know if you have any additional questions or please set this thread as resolved.

Kind regards

Kevin Brosnan
Tier 2 Senior Technical Support Engineer

CompTIA Security+ Certified

OK.

Thank you very much for your help. The subject can be considered solved and closed.

Kind regards

Witold Konieczny