check this out, not exactly a limitation, works with gmail app as well as profimail
Tutorial to use the ES File Explorer to attach many files to an email
• Launch the ES File Explorer on your android device.
• You will immediately see a list of files and folders.
• At the top of the ES File Explorer screen you would see the Select button. Tap on this button.
• Here you will see “Multi-Select Ready…” as a popup notification at the bottom
• Tap away to attach the desired files. Selected files will be highlighted.
• Tap the Menu button on your android device.
• Tap Operations and Select Share from the popup list
• Select Gmail or any other mail app you use
• The selected files will show as attachments in the email message.