Can't send e-mails due to IP address blacklisted due to "rDNS"

[JCmacc]

Via Outlook I can get incoming e-mails from our 2 ntlworld accounts but can not send as our IP address has just been added to a blacklist apparently. I've checked various websites and the IP address hasn't been flagged for spamming and there's no evidence of any hack or unknown sent e-mails, nor have we been sending any great number. 

One diagnostic site tells me the blacklisting is due to a change being needed by the ISP. The message is below.

"This IP has been flagged because it is dynamic or by suspect to be domestic use only.

If you are running an email service on this IP, ask ISP to change the rDNS

The removal of this IP from this blacklist depends on change of rDNS to match the FQDN of the mail server."

This did occur just before the Hub needed a reboot (as evidenced by an Amazon Firestick issue that was fixed by the Hub reset). One question is did the Hub error cause a DNS change that resulted in the black listing? 

Any advice on the issue and/or next steps would be greatly appreciated.

[coenoby]

@JCmacc 

These days you could say that the VM service as a whole is legacy.

VM stopped issuing new email accounts in May 2022. Since then new broadband customers have to use their own email accounts and existing customers can no longer create new secondary email accounts.

As a result the number of active VM email accounts will continue to fall and it's not clear what the future holds for the VM email service.

Coenoby