Yahoo! mail requires several change in SecureSchool to allow it to be loaded correctly. Several websites need to be added as unfiltered sites, and Port Access rules need to be created for some other Yahoo! sites.
SecureSchool, ISBossBox, LibraryDoor
First, you need to unfilter some of the sites involved. Go to "Website Filtering" -> "Website Access" -> select a filter set (if you have different filter sets) -> "Add a Site". Add the following sites as "Unfiltered" sites:
Next, you need to allow HTTPS access to some of Yahoo!'s servers. Allowing HTTPS access to all of Yahoo! would be bad because it would allow encrypted searches, and SecureSchool would not be able to filter the results. To allow the HTTPS sites needed, go to "Website Filtering" -> "Port Access" -> select a filter set (if you have different filter sets) -> "Add An Allowed Port Rule". Add the following sites for port 443 with a type of "SSL/HTTPS":
Lastly, you will still have problems with attachments. This is because yahoo uses bare IP addresses to load content from their attachment servers. Accessing bare IP addresses is usually blocked in most Filter Sets because most sites that use bare IP addresses are not desirable sites. If a user has a problem downloading attachments from Yahoo! Mail, you have to search in the Filter Log ("Logs & Reports" -> "Filter Log") for the user's IP address, and find the site that is getting blocked. It will be similar to "http://18.104.22.168/us.f598.mail.yahoo.com/ya/securedownload?", but longer and with a different IP address. You need to add the IP address of the site as an unfiltered site under "Website Filtering" -> "Website Access". For the link given as an example, you would add "22.214.171.124" as unfiltered. Yahoo! has many different IP addresses hosting mail attachments. Unfortunately this is just a process you must go through, and eventually you'll get all the IP addresses serving your area.