If your spam folder contains a large number of messages (1000s), trying to clear it out a page at a time using the SquirrelMail default settings would take forever. However trying to do it in one go (by selecting Show All, etc) results in a time-out because there are too many messages to handle at once. The practical way is to increase the number of messages shown per page then Toggle All and delete the much larger page-full one page at a time, occasionally clearing the Trash folder, and repeating until done.
To increase the number of messages per page:
Login to webmail (SquirrelMail)
Click Options
Click Display Preferences
Change "Number of Messages per page" to (say) 250
Scroll down to the bottom of the page and click Submit
Then, to Delete spam messages:
Click the Spam folder to display its contents a (longer) page at a time
Click Toggle All to tick all the messages on that page, then
Click Delete to move them to the Trash folder
A new page of headers should be displayed. Repeat Toggle All/Delete.
When you have done 1000-1500 it is a good idea to empty the Trash folder.
To empty the Trash folder:
Click Check Mail
The text "(Purge)" should appear against Trash in the folder list. Click that word to empty the Trash folder.
Repeat the above operations as necessary to delete remaining spam messages. Done this way dealing with a very large number of messages becomes practical.
