I would expect your colleague to say that they recognise that IP address. It is one of the addresses used by VM's servers in NW England to handle outgoing mail from customers' email client programs like Outlook. It is an SMTP server (in the jargon). If mail from that address is getting that error when it sends mail then the recipient server is obviously seeing the mail as spam and delaying it (grey listing). In fact the IP address is blacklisted currently on SORBS SPAM according to MX Toolbox. It is not the customers IP address that is being blacklisted.
It is about time VM's email team started to monitor properly the state of their mail servers which are being detected as sending spam. The servers in NW England in this IP range should be clean and kept clean. If they do get blacklisted that should be dealt with quickly by the VM email team to stop customers experiencing this. No customer should ever see this error type. The customer is an innocent party here.
I will add this, and I am being careful what I say here. There is a server range in NW England that VM use to send mail from email clients where they suspect the mail to be "dirty". That is definitely not the case here.
Over to VM IT security to get the backlist sorted please. Other customers are affected too as the IP range assigned to outgoing mail is variable and this IP address will be used many other customers.
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