who is responsible to remove our public IP from black list?

Hello experts,
A small company has web site hosted at (x-company) and static IP from an ISP company, and web hosting  company give them email services too. unfortunately a user got a virus and his PC became spammer so he could not send email anymore. I cleaned the PC and recreated outlook data file (PST) and seems he is okay now and can send and receive emails but the wan IP and DG are still black listed on two databases. at this time I want to know besides implementing firewall and antivirus for the company.
who is responsible to remove the IPs from black list?
what else I could do to minimize the incident to be repeated?
Thank you.
OscarIT supportAsked:
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It pretty much depends on which list you are on.  Some will release after a period of non spamming others require act from you, like filling out a form.
here are a couple of articles about getting unlisted:
Good luck

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Were you able to get unlisted?  That is what counts.  :)
OscarIT supportAuthor Commented:
Yes, one of the site was cleared after PC was cleaned and the other site is mentioning that if we don't host email server on our site then we should not be worry about it. by the way IP from birch or Cbeyond are the worth IPs according to them,,
Thanks any way for following up
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