Working for a company which allows ads for haraam things on its web pages
Question

I am a member and writer for a very well-known mailing group, which rents space on its page to an international site to publish whatever it wants, and of course it receives payment for that. One time I saw in the space that is allocated to this company an advertisement or announcement for a disbelieving website that speaks about witchcraft and fortune telling. My question is: is there any sin on me or any consequences for continuing to write for this famous mailing group?
Praise be to Allah.There is nothing wrong with you remaining in your job, because the sin is borne by the company, not you, because you – according to what you say in the question – play no role in the publishing the haraam ads or corrupt websites. But that does not absolve you of the responsibility to advise the company for which you work, and to remind them to fear Allah, may He be glorified and exalted, in the hope that they will accept your advice and put right what they have corrupted.
May Allah reward you with good for your keenness, prudence and interest in finding out the shar‘i ruling.
See also the answers to questions no. 31781 , 98062 and 107677 .
And Allah knows best.