Mail Vault downloads all your mail and allows for fast searching for online and offline access.
Several years worth of emails can be searched quickly.
Key features
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• Download and store email from nearly all IMAP accounts
• Search To/From/Cc/Bcc/Subject
• View your email by folder
• Reply, Forward, and Compose new mail
• Delete Mail on the Phone or Server
• Multiple Accounts
• HTML email viewing
• View many attachment types
• View raw mail HTML, Plaintext, and Headers
• Support seen message flag
• Only show attachments view
• Bulk message delete in search