Go vote on this feature request:
Bug 16898 – Delete messages based on a search query (like older than 1yr)
the lack of this feature is a testament to how horribly shitty zimbra is. i need command line admin access to delete more than 100 messages at once? i need to be using a third party desktop client to delete more than 100 messages at once? what a joke. i have +56,000 messages in my inbox. my email client (god forbid i actually use the zimbra interface to read my email - i'd rather scratch my eyes out) is crippled by this volume so that won't work. so this means i have to find someone in my organization with admin access to enter some command line prompts to delete some freaking messages? isn't that what an email service is supposed to do on it's face? yet another reason i will never use zimbra again.