Email permit sending files and documents in the form of attachment. Some even use such facility as a free online storage. Emails however have a cap in how big an attachment be.

Here are the limits of attachment sizes in big players in email sector: Hotmail, Yahoo and Gmail :

Hotmail : 10GB (since August 3, 2010, in SkyDrive) – Unlimited storage
Yahoo : 25 MB attachment limit – Unlimited storage(since May 2007)
Gmail : 25MB (since June 2009) – 7GB storage

There are other email service providers but, none is near the three market leaders.