After that, I took a different approach: I kept sending the mail on the SAME server as the backup, and using IMAP I could DRAG-and-DROP the backup attachment from the mailbox on one server to the mailbox on another server (=GMail). They did not mark me as a spammer that way, of course.
So that worked for a while, but then I got tired of doing this manually.

So the following ruby script is the way I automated the "move offsite" part of that backup.
For completeness, I will give the due credits about who set me on the right track: I started off by this example by Ryan.

#!/usr/bin/env ruby
begin_ = Time.now

#includes
require 'net/imap'

##Source Info
$SRCSERVER="mail.muscetta.com"
$SRCPORT=143
$SRCSSL=false
$SRCUSERNAME="daniele"
$SRCPASSWORD=""
$SRCFOLDER="INBOX.Backups"

##Destination Info
$DSTSERVER="imap.gmail.com"
$DSTPORT=993
$DSTSSL=true
$DSTUSERNAME="muscetta@gmail.com"
$DSTPASSWORD=""
$DSTFOLDER="Backup"

#connect to source
puts "connecting to source server #{$SRCSERVER}... \n\n"
srcimap = Net::IMAP.new($SRCSERVER,$SRCPORT,$SRCSSL)
srcimap.login($SRCUSERNAME, $SRCPASSWORD)
srcimap.select($SRCFOLDER)

#connect to destination
puts "connecting to destination server #{$DSTSERVER}... \n\n"
dstimap = Net::IMAP.new($DSTSERVER,$DSTPORT,$DSTSSL)
dstimap.login($DSTUSERNAME, $DSTPASSWORD)
dstimap.select($DSTFOLDER)

# Loop through all messages in the source folder.
uids = srcimap.uid_search(['ALL'])
if uids.length > 0
	$count = uids.length
	puts "found #{$count} messages to move... \n\n"

	srcimap.uid_fetch(uids, ['ENVELOPE']).each do |data|
		mid = data.attr['ENVELOPE'].message_id

		# Download the full message body from the source folder.
		puts "reading message... #{mid}"
		msg = srcimap.uid_fetch(data.attr['UID'], ['RFC822', 'FLAGS', 'INTERNALDATE']).first

		# Append the message to the destination folder, preserving flags and internal timestamp.
		puts "copying message #{mid} to destination..."
		dstimap.append($DSTFOLDER, msg.attr['RFC822'], msg.attr['FLAGS'], msg.attr['INTERNALDATE'])

		#delete the msg
		puts "deleting messsage #{mid}..."
		srcimap.uid_store(data.attr['UID'], '+FLAGS', [:Deleted])
		srcimap.expunge

	end

	#disconnect
	dstimap.close
	srcimap.close
end

total_time = Time.now - begin_
puts "Done. RunTime: #{total_time} sec. \n\n"

In fact i consider GMail as being one of the best interface for reading mail that exist out there - I love "tagging" (oops: it's called "labelling" in their syntax), speed of search through messages (even tough Outlook 2007 is faster on indexed content, but still you have to buy it and install it on your PC)… I also especially love the way it shows THREADING… so that I moved pretty much EVERY mailing list I read on their account:

(ok, they could do better with the localized version of "Re:" in replies…. in Italian a lot of broken MUA's translate that into "R:" and that isn't understood by GMail and will make it think it is another thread…. but that's a minor issue, and also one that every MUA handling threading has - including "mutt" - the real problem is the broken MUAs sending the "R:" in the first place. But I digress too much….).

I also keep GMail continuosly opened in a browser during the day because a lot of informative mail and that sent by friends goes there. This to say that I do get a lot of their ads (that is - the point of having such an application, for them…). On the contrary, Windows Live Mail reduced its ads to show only one… not to annoy you too much.
But the ads in GMail were not *really* a problem (I don't read them anyway, I just plain IGNORE THEM).

But this week they REALLY pissed me off. They REALLY have. And here is the reason:
I have been using a script for MONTHS to backup my database (the one powering THIS blog) and send it "off-site" to my GMail mailbox. Pretty much something like a lot of other people do, described in various articles and blog posts. Then I was labelling them with a rule, so that I could access my backups easily in case I needed them.

Now I don't know if this violates their terms of use in any way… because I am not really using it as storage with those programs that circulated at one stage that had "reverse engineered" it. Those were bypassing the web interface altogether so people did use it as storage with a program without having to see their ads. That was the issue, I think. In my case, I am just sending MAILS to myself. One per day. I also delete the old ones every now and then, and they are not even huge in sized (attachments of 40 to 50KB so far!!)… anyway, I know a lot of people that store documents and all sort of stuff even in their corporate mailboxes in Outlook (then maybe index them with Windows Desktop Search of Google Desktop to find it back)… I was only doing the same with GMail. I don't see the big issue here….. they might think otherwise…. but from what happens I don't think that's the issue.

Anyway, now it's been three or four days that my backup mail gets rejected. My SMTP Server gets told:

host gmail-smtp-in.l.google.com[66.249.83.27] said:
550-5.7.1 Our system has detected an unusual amount of unsolicited
550-5.7.1 mail originating from your IP address. To protect our
550-5.7.1 users from spam, mail sent from your IP address has been
550-5.7.1 rejected. Please visit
550-5.7.1 http://www.google.com/mail/help/bulk_mail.html to review
550 5.7.1 our Bulk Email Senders Guidelines.

Now for fuck's sake. You know how much I hate SPAMMERS and what I would like to do with them. But I also know that it does happen to end up in RBLs and such sometimes. Fine. But GIVE ME a way to tell you that I am NOT one! If you go to the link above, all you find is a form where you can specify that mail that ended up in your "junk" folder actually wasn't spam. Yeah, right. In my case it does not even go into my "junk" folder! How am I supposed to give me the original header that arrived to THEM if I only have the one sent by my mailserver ? They just blacklisted my mail server's IP Address! As they say, I even have an SPF record, I always use the same address, etc….
So I tried to fill in the form, the day after I also tried to contact their abuse@google.com and abuse@gmail.com addresses.
Still nothing.
They even tell you (in the automated reply when you contact "abuse":
"[...] For privacy and security reasons, we may not reveal the final outcome of an abuse case to the person who reported it. [...]".
How great. How am I supposed to know if they even READ my complaint ?

You anti-spam people at GMail: "I am NOT a fucking spammer!!!!!". I 'haven't found a better way to tell ya this, you know, than writing it on my blog… this is just RIDICULOUS!

But to date my mails still get dropped. I'll probably have to send my backups somewhere else. At this point they pissed me off so much that I am also seriously considering getting back to use my own mailserver also for receiving and reading my mailing lists. Then I won't get ads there.
Afzetterij!
(I hope you have some dutch guy on board at Google, as "Google Translate" does not translate from/to dutch yet…. )

Edited on October, 8th - While GMail REJECTS those mails (it SAYS it is not accepting them), Hotmail simply DROPS them (that is: it does not even SAY it is not accepting them):

to=, relay=mx4.hotmail.com[65.54.245.104], delay=3, status=sent (250 <20061008061010.GA19807@muscetta.com> Queued mail for delivery)

This way you THINK it is going to be delivered, but it NEVER shows up in your inbox. I don't know who's behaving the worst…