To search for attachments in Gmail, the search parameter is has:attachment – this will bring up all emails with an attachment. If however you wish to find attachments over a certain size – to clean up your email – you can do this using size:.
So, to search for large attachments you could use the search size:10M – this will show all emails with attachments larger than 10MB
Combine this search with the older_than parameter to find mail older than a certain period. For example older_than:2y will find mail more than 2 years old; older_than:30d finds mail over 30 days old.
If you still use Outlook take a look at this tip on how to find large attachments in Outlook.
Let us know what you think of this tip in the comments below.