Email exceeds size limit?

[#1]

I suddenly unable to send email; a one-line email fails with a dialog box saying:

Quote

The size of the message you are trying to send exceeds a temporary size limit of the server. The message was not sent; try to reduce the message size or wait some time and try again. The server responded:  ... temporary failure

Using Thunderbird 7.0.1 on Windows 7.
Any ideas?

[#2]

That's rather a weird problem. No problems sending messages for me using Thunderbird 7.0.1 on Vista SP2.
Does the error repeat if you send the message again?

[#3]

Yep. I am completely unable to send email at the moment. I'm about to try rebooting the PC to see if that helps. And/or rebooting my ADSL router...

[#4]

Rebooting the ADSL router seems to have fixed it.

[#5]

Hi jamie, glad it's working now Please let us know if there's anything we can look at for you.

[#6]

Nope. That only fixed it temporarily. It seems I need to reboot the router almost every day before I can send email.

[#7]

Now even rebooting the router doesn't seem to fix the problem ....

[#8]

Can you send any email at all using webmail?

[#9]

Yes, webmail works.

[#10]

OK. I just tried sending email from Outlook and got a more helpful error message. It seems the problem is that I was using another domain name for my email address. Setting my email to jamie@domain.plus.com fixes the problem. But this is not very satisfactory as I want people to see email coming from my company domain name.
Should there be an MX record for mydomain.co.uk ? If so, what should it look like? (I have never fully understood these DNS records)

[#11]

Do Plusnet host the domain?

[#12]

I have added a DNS record:
<blank> | mx | 20 | mx.last.plus.net.
This seems to work. I hope it is the right thing...

[#13]

Quote from: jelv

Do Plusnet host the domain?

Well, the domain is registered elsewhere but points to Plusnet's domain name servers

[#14]

Who handles the mail for the domain?

[#15]

Quote from: jelv

Who handles the mail for the domain?

Well, it is (should be) all handled by plusnet. That is certainly what I want to happen! And it has all been working perfectly until very recently.