If you do not know how to change this, if necessary, you should talk to your local support folks. The suggested length of signatures on Usenet is four lines. On this list, where many people post several times a day, it is probably safe to assume that people will remember who you are after the first post. Therefore, attaching an 8 - 10 line signature to every post is seen as antisocial. Don't do it.
Some people pay for every byte of mail they receive.
Some people pay phone charges to download their mail. Yes, your off-topic postings can inconvenience people. Yes, your long signature is costing people money. No, they can't just ignore it. So don't be so damn selfish.