While Google's popular e-mail service has taken the world by storm, it lacks one big feature. This is the ability to sort your e-mail messages by size.
So, if you get a mail size warning from Google asking you to clean up your box, you typically end up using the search function. You do this by using the 'Show Search options' located in the top bar.
Another solution is to use the 'filename:' command in the Search Mail box to quickly find out messages which have attachments. For example, using filename:ppt will fetch you messages that have power point slides as attachments.
But, the most simplest way to do this is to use an online service that allows you to sort and find your large messages in Gmail. The advantage - you do not have to download or install anything.
The website is called findbigmail.com
All you have to is enter your gmail address. The website will then ask you permission to access your gmail account. Then click the Grant Access button. The website will proceed to scan your gmail inbox for large messages. Depending on the size of the inbox, it will neatly categorize large messages such as: FindBigMail > 2 Mb, FindBigMail > 500 KB. This can be seen on the right hand side of your Gmail inbox. If you click on any of these labels (say, FindBigMail > 1 Mb), you will get all the messages that are greater than 1 Mb.
You can now quickly select the large messages and delete the ones that you do not want. You can also avail of a free scan report that the website sends to your gmail id after the complete scan.
Access the website at: findbigmail.com