Receiving email but issues sending

[#1]

I've noticed other people have had the same complaint over the last couple of days.  I use Plusnet as our business email, routed through to Windows Live Mail.  Over the last couple of days it's been stopping me sending emails.

I've scoured the internet to try and resolve the issue below, but now it seems I'm not the only person having issues with Plusnet:

The message could not be sent. The setting for your outgoing email [SMTP] server might need to be configured. To find the server settings for '****@hotmail.com', please contact your email service provider.

Subject 'Re: Cancel'
Server Error: 452
Server Response: 452 Too many rcpts in time period from this IP
Server: 'smtp.madasafish.com'
Windows Live Mail Error ID: 0x800CCC79
Protocol: SMTP
Port: 25
Secure(SSL): No

It is sporadically sending emails but if I can only send max of three before it stops me sending and coming up with that error, despite it only being sent to one email address.

Has anybody had luck in resolving this issue?

[#2]

I am having a similar problem.

For many years I have used Thunderbird,  a Plusnet email and we have a broadband account with Plusnet.

Over the last week Plusnet  has intermittently refused to send emails from my plusnet email via the Plusnet server.  Message says something like "email too large or too many emails from this ISP at this time" (will copy exact text next time it appears).  Doesn't seem to relate to size of message - today refused to send an email which was a few lines long, only two recipients and no attachments.  I do often send via our Virgin broadband connection rather than Plusnet, but I don't think this was the problem as it still refused after I switched to the Plusnet connection.

Have checked all server settings which look ok, and most of the time it works without any problems.

Have had to resort to sending from my gmail account - getting very frustrated.

Anyone else had these issues?