PSTCompactor - Home Edition 

Shrink Microsoft Outlook email PST files up to 38% and avoid the 2gb limit - don't let Outlook corrupt your email. Zip attachments, force compaction, removing deleted content and more! Makes Outlook faster, more reliable and less prone to corruption
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PSTCompactor - Professional Edition 

Reduces Microsoft Outlook PST file sizes up 38% across the Corporate network. Compress & zip attachments, automate compaction, etc. Suitable for management and implementation of Enterprise Email Policies. No Exchange changes or dependancy
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E-Rkive 

Archive e-mail with E-Rkive. The program interfaces with Microsoft Outlook, allowing you to archive, restore, search, filter and compress e-mail.
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