Drro,
I read your OP a few times. I am assuming you are just a regular Delancer customer using a Delancer modem to connect to the Delancer DHCP server for your IP assignment. Correct so far?
The terms of service for most ISPs specifically prohibit the the use of their email infrastructure for the distribution of mailing lists and commercial endeavors unless you subscribe to some sort of commercial account with that ISP (if available, not available with Delancer). Even though Delancer just grabs your money and you never sign anything saying you understand all the terms and conditions, you are still subject to them. A commercial ISP will maintain "MX and SPF" records in your DNS listing which will significantly help in cutting down on your email getting flagged as spam.
Neither Delancer nor Comcast provide these services nor maintain the DNS records to permit anything but your average customer asking their Mom for money via email. Delancer assigns you a non-routeable IP address and the very fact that systems outside of the Delancer network cannot get a valid MX or SPF for your individual IP address causes problems. All it takes is for a few people to hit the "this is spam button" rather than taking the time to unsubscribe from your mailing list and voila, you start appearing on spam lists as the recipient's ISP begins to report your individual IP as the source of mail their customer(s) do not wish to receive. Backed up by the fact that your DNS does not identify you as an established safe email origin and because your IP address is unreachable to outside systems, your inclusion on the lists is all but guaranteed.
That's how you get on the lists. Getting off the lists requires time and effort and probably will not work, again because your IP presented to the outside world beyond Delancer and Comcast, is not reachable and not identifiable. Each list, and there are a bunch of them, all have their own policies and mechanisms for individuals to remove themselves from the list. Good luck with that.
Individuals that maintain mailing lists should really source a better delivery mechanism than their own ISP unless they have a commercial account. It is only a matter of time before your personal subscriber IP address gets blacklisted. Eg. If I email my Mom and ask her to send money and instead of her just deleting the message after telling me, "No", she hits the "this is junk" button enough times, I'll get reported. Luckily for personal correspondence, most recipients just delete the one-off emails they receive from people they know. For mailing lists and other bulk emails, most recipients do not take the time to actively classify the emails as "not junk" to export the the email from their spam folder, they just delete them. Or to get a repetitious email out of their already cluttered inbox, they just hit the "this is spam" button and poof that email and all subsequent emails from the same entity never show up in the inbox again. Easy peasy as they say.
So going forward what do you do?:
1) Get a Claro account that is a routeable IP address and run your own email server on your own domain address so you can provide a MX and SPF DNS entry to make most other mail servers happy again. Still probably a violation of the terms of service for a noncommercial Claro account but who cares.
2) Subscribe to a bulk mailing system where you login, upload your email and it gets sent to the list of recipients you configure. The service takes the hit when your messages get flagged as spam and because they can maintain their DNS entry with the appropriate entries individual recipients won't be able to flag their system as a spammer unlike what can happen to a private individual with no control over their DNS record.
3) Visit all the lists that you find yourself on and file a request to have your IP address removed.
Expect no help at all from Delancer or Comcast. If you continue to send out large volumes of email at regular intervals from a standard user account, even if you change IP addresses, this will become a reoccurring issue. The ISPs don't want you and others choking their email servers, so most do not care if you get blacklisted or not.
