Google Mail is awesome. You can use it as an alternative to exchange, or even for personal use. As some GApps administrators may have seen in the past, users love to archive everything (you may even do this in your account). Google gives you 25GB of space for your Mail account, which may seem like a lot, yet there are some users who use all of it.
In order to find those large messages and attachments there is an undocumented size search operator that you can use, which will find mail messages greater than a certain size. Example search queries below, which can be clicked on to search within your Google Mail account:

Find Messages/Attachments Greater than 5MB:
Find Messages/Attachments Greater than 10MB:
Find Messages/Attachments Greater than 20MB:
** Additional Tip ** You also have the option of using: size:5MB, size:10MB, size:20MB, etc as well.
TechSmog

Is there a way to strip the email of its attachment?
Not in the web interface, but it’s possible if you use a desktop client with IMAP.
with imapsize you can delete attachments (all or individual) without downloading them:
http://www.broobles.com/imapsize/
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Display of all mailboxes in an account with visual alerts for the most space consuming mailboxes
Convenient storage quota display
Powerful search capabilities on single or multiple mailboxes
Delete attachments (all or individual) without downloading them
Save attachments locally from multiple messages (BETA)
Mailbox management (expunge, create, delete, rename)
Message management (change flags, copy, move, delete, etc)
Manage folder subscriptions
Modify message headers
Copy messages from one IMAP account to another
Perform incremental backups of multiple folders in your IMAP account
Perform incremental backups of the whole account
Replicate IMAP folder hierarchy to your local drive
Download/upload messages to/from mbox and eml files
eml2mbox conversion
mbox2eml conversion. This can be extremely useful in the process of moving messages from Thunderbird to Outlook. Here’s how.
Spam handles which provide a basis for visual alerts on spam messages
SSL connections
Minimizes bandwidth consumption wherever possible
Keyboard friendly – you can perform almost all operations without using the mouse
Great, thanks, have saved some extra room from emails that were years old!
It also works with from: but didn’t work with date: but then I only tried on date format.
Works with From: also.