Mailing out directly over ADSL or FTTC lines. Ok?

[#1]

I have a client who inherited 75000 email addresses from a defunkt company he bought.  We want to send an email out once only to this list inviting them to join the new company's list.
As the source of the 75k can't be verified it is possible that MailChimp etc would freeze the account.
Plan is to use Gammadyne to directly mail out over our FTTC line. We will create a domain to point to the line's IP address and set it up correctly.
Has anyone tried direct mailing through PlusNet lines before? PlusNet support couldn't advise and suggested this post.
All advice gratefully received! Pete

[#2]

Hi Pete,
I'm not familiar with Gammadyne however if it mails straight to the recipients' mail exchanger without relaying through our outbound servers, then you should be fine. If you're pointing a domain to your IP then I'd also suggest you ask us to map the reverse DNS of the IP to your domain (you'd need to raise a support ticket to request this).
The reputation of the IP we assign to you isn't likely to be very good so I'd expect <b>*lot*</b> of the mail to be bounced/spammed or otherwise ignored.

[#3]

Hi Bob
Thanks for the advice much appreciated.
We plan to send a few 'clean' email runs to gain some kind of reputation. Short with at least a day between sends....
Best regards, Pete