You don't as far as I know, it's up to the recipient to set there spam filter to allow emails to go into their inbox. Not sure about google but yahoo sends all unknown emails to the bulk folder, and you then set the mail address as "not spam" so the next time you send an email it will go into the recipients inbox and not the bulk folder. Question what method are you using to send emails, are you using a bulk send mail php / asp program ? as most mail folders MSN, AOL, Yahoo will dump it in the spam folder because it's server sent. hope that helps. UK Charity and none profit making groups can list details at tradersreview.co.uk/community for FREE
Thanks for your reply. Yes I am usong OEMpro to send my emails.... Comcast, for example, has a page that you can request to be allowed: http://www.comcastsupport.com/sdcxuser/lachat/user/Blockedprovider.asp
Chiefly speaking, once the mail server sense that when there is incoming bulk mails, it would flag them as bulk or spam. There is nothing much you can do really, you just have to inform your opt-in members to whitelist your email address.