I am not sure how to zip a file using the 7zip program.
I use outlook and it is blocking the file because of a possible unsafe condition.
Do you mean MS Outlook or Outlook Express as they are totally different, but they are both the pits when it comes to draconian measures that they say protects against malware. They don't allow certain file types to be attached, believe it or not .zip files are one such type (I don't know if that includes .7z), .exe only because they 'could' contain viruses, which is absolutely pathetic.
In Outlook Express 6 from the Tools, Options, Security tab, uncheck the 'Do not allow attachments to be saved or opened that could potentially be a virus,' see image. Talk about pathetic, no checking for actual viruses, or consideration that your AV checks or that you might just know what you are doing, just a blanket ban on what they consider suspect file types.
Now it you are using MS Outlook, you will have to try and find the equivalent option in MS Outlook.