Oh, welcome to webmaster world. :)

If you ever send newsletters that have not been requested, a proportion of the recipients will mark it as spam; depending on the topic and the quality of the content, that could be a large proportion - and depending on how many you send, that could be a large number of spam reports.

That, in turn, can permanently damage the credibility of the sending address - even for those who requested your stuff.

Start again;

1. Build a new database of members who have 100% opted in - and set up a new mailing service for them.

2. Be sure your newsletters give information on opting out - if people can opt out, they are less likely to report you as a spammer.

3. Be sure the newsletter delivers what it promises; if it could be seen as no more than a marketing sheet, readers will act appropriately.

Put yourself in the readers' shoes; what do you find acceptable, and what makes you report spam?

Remember also that many modern email systems (eg gmail) make it very easy for spam reports - and most people get so much, that they will no longer give you the benefit of the doubt.