20 Essential Gmail Tips You Probably Don't Use (but Should!)
Set up Automated Canned Responses for Quick Fire Emails
We admit it, we're hypocrites, but hear us out. Sure, we despise as much as the next person receiving an automated response to a customer support inquiry, so why in the world would we advocate setting up Google's so-called Canned Responses? Put simply, we can be much more efficient and less burnt out by composing pre-set replies to common questions we receive all the time.

To take advantage of this feature, head back into the Labs tab (under Settings), enable Canned Responses, and mash the Save button. Now let's say you placed a For Sale ad on Craigslist or your local Classifieds and the item sold, but you continue to receive inquiries. It can get pretty old typing out the same response over and over, and it's bad etiquette to just ignore the email. After all, you may be shunning a future buyer for other items you may list for sale.
This is where Canned Responses come in. Type in your response. In our example, we wrote, "The 2008 Pontiac GTO I listed on Craigslist is sold. Thank you for your interest." It's short, polite, and to the point, and it's also generic enough to be used no matter what the question is regarding the car that was recently sold. To save this message as a Canned Response, click on the Canned Respond link in the upper right corner, select Save, and give it a name.

The next time an email comes in asking about the car, we can simply click on the Canned Response link and insert our pre-composed reply.

To take it a step further, we can automate the process of sending Canned Responses by using Filters. To do this, click on the Create a Filter link next to the search box. In this example, we want to filter emails that contain the words 'Craigslist,' 'Pontiac,' or 'GTO.' We'll write these down in the 'Has the words' field with each word separated by the search operator 'OR' (in all caps). When you're finished, click Next.

In the next step, mark the 'Send canned response' checkbox and select the appropriate one from the pull-down menu. You can also choose to mark the email as read, delete, archive it, and a few other options. When you have it configured the way you want, mash the Create Filter button and let Gmail handle the rest!
Send and Receive Blocked Files
Thank virus writers and malicious malware miscreants for the restrictions most ISPs and email services place on potentially dangerous file types. That includes Google, which blocks you from sending or receiving executables, as well as some other file formats, even if they're sent in a one of these compressed file types: .zip, .tar, .tgz, .taz. .z, and .gz.

The easiest workaround is to amend the file extension to fool Gmail into allowing the file, and then let the recipient know they'll need to rename the file. For example, let's say you coded a simple app and wanted to share it with your mentor. Open up the directory where the file is located and press the Alt key to bring up the menu bar. Click on Tools>Folder Options, select the View tab, and uncheck 'Hide extensions for known file types.' Hit OK.

Now you can edit your file's extension. Right- click the blocked file and select Rename. Add .REMOVE to the end of the file, so for example CustomApp.exe would become CustomApp.exe.REMOVE. A pop-up window will appear letting you know that if you change the extension, the file might become unusable. Click Yes, as once the recipient changes it back. it will be fully usable again. Now you're free to send your file!
Protip: If you have a lot of blocked file attachments to send, compress them into a single .zip file and then change the .zip extension in the same manner above.

If you're not comfortable thwarting Gmail's virus scanner, you still have other options. One of our favorites is YouSendIt. Once you register, this free service will allow you to send any file type up to 100MB in size (By contrast, Gmail limits messages to 25MB). If you need more than that, there are also several subscription plans available starting at $10/month.
To use the service, just log in, attach your file, and fire away. Once the file is uploaded to YouSendIt's servers, the recipient will receive an email with a download link that's good for 7 days. Groovy!