Spam training rejected my emails

[#1]

I'm getting a vast increase in spam and Postini doesn't seem to be able to cope with it even though I have been using the Spam button in webmail to notify if of the messages. I decided to try using the email method in Thunderbird as advised in this PN Help page:
http://www.plus.net/support/security/spam/forwarding_spam.shtml#thunderbird
But although I sent them as attachments and as advised on the page they are being rejected:
********************
This message was created automatically by mail delivery software.
A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:
  spam@spamtraining.plus.com
    SMTP error from remote mailer after end of data:
    host mx-postini.core.plus.net [64.18.4.13]: 552 Too many recursive MIME attachments
*********************
Too many? What is the maximum we are allowed to send at one time? I'm getting hundreds of spam messages.
When these spam messages arrive on my PC Thunderbird deals with them because I use it's filters to ditch any messages sent to my domain that do not have a valid email name before the @ symbol, i.e. for messages sent to my domain name I tell Thunderbird to only let through those with a specified set of email names before the @. Is there a way on Webmail/Postini that I can mimic what I do on Thunderbird so that they don't have to download in the first place?
Thanks!

[#2]

Quote from: Bookman

When these spam messages arrive on my PC Thunderbird deals with them because I use it's filters to ditch any messages sent to my domain that do not have a valid email name before the @ symbol, i.e. for messages sent to my domain name I tell Thunderbird to only let through those with a specified set of email names before the @. Is there a way on Webmail/Postini that I can mimic what I do on Thunderbird so that they don't have to download in the first place?

Yes there is. The Spam Protection Guide available from the Help and Support pages will guide you through the necessary steps, which use the Manage My Mail (MMM) tool on the portal (login required). This can also be accessed through Member Centre->Email Settings->Manage My Mail.
What you are already doing is to define a number of acceptable addresses - aliases in the MMM terminology, managed through the Aliases tab. You must already have a default mailbox, and the acceptable aliases are pointed to this mailbox (or another one if you wish). If Catch-All is turned off, anything to any other alias is dropped (before it reaches your PC).

[#3]

Thanks spraxyt, I'll have a look at that when I get a chance. I've seen these words catch-all and alias before but never known what they are about. I have a busy time running my own business, which is unrelated to IT, and I try to keep everything about computers as simple as possible. But sometimes, "needs must"!

[#4]

I've just realised that I didn't get any response to the first part of my original post - is there a maximum number of spams that can be sent to spam@spamtraining.plus.com in one email message? My attempts to send multiple attached spams are being rejected with the "undeliverable" message shown in my first post above.

[#5]

I didn't try to answer that part of your previous post because I can only give an opinion, not a definitive answer. In fact I'm not sure there is such a thing.
I suspect what you are seeing is one of the tricks spammers use to make it harder for content filters (like Postini or Junk Mail in Thunderbird) to analyse the mail contents. That is they use malformed MIME headers. When you forward such messages as attachments to another message, because the headers are incomplete the boundaries of each attachment are unclear and the mail transfer agents would probably loop, run out of memory and crash if left unchecked. I think what that means is the answer you are seeking depends on the particular samples you are trying to forward.
So just a single attachment will work, two probably, five who knows?
Since you have so many unidentified spam messages I suggest you just send a sample of these, perhaps a couple of each style - if such is recognisable.
Longer term if you work through the steps set out in the Spam Protection Guide I would expect much less spam to get through to your computer and perhaps forwarding will work for that reduced volume.
Hope this helps.

[#6]

Thanks for the further advice. As you suggested, I've now set up my email names as aliases in Manage My Mail and switched off Catch-All on my main mailbox. This has reduced to a trickle the amount of post-Postini spam coming down to my Webmail Inbox and my PC, while the white list makes sure I always get the essential messages. 
The PN guide and the Manage My Mail tabs were very straightforward, so full marks to those who designed the pages and the facility!