Getting repeated 452 errors

[#1]

Over the past few days I am getting repeated 452 errors when trying to send email using smtp.

Error Message:

Your message did not reach some or all of the intended recipients.

      Subject:     ***

      Sent:  07/09/2018 14:30

The following recipient(s) cannot be reached:

      '*@*.com' on 07/09/2018 14:30

            Server error: '452 < > too many recipients in the last hour'

I certianly have not attempted to send many emails in the past hour.  I use Outlook 2016 as my mail application on my main PC but I have checked on a spare machine (Outlook 2010) and Laptop (Outlook 2010) as well as my wife's pc Outlook 2016.  All with the same result.

No problem sending via 1and1 smpt server or via gmail.

[#2]

Hi there.

Are you unable to send mail by logging into http://webmail.plus.net too?

[#3]

Hi Gandalf

Thanks for your interest.  Yes webmail is ok as you would expect as it does not use the smtp server relay.plus.net

I posted a PN ticket on this yesterday at ca 1700 but over 24 hours later no response from PN.  Not such good service s we used to have some years ago from PN.

[#4]

No worries and sorry that you haven't had a reply to your ticket yet.

I've raised this with our infrastructure engineers for investigation and we'll update you when we know more.