Sometimes it’s useful to allow others to use your Gmail account for a temporary period. For example, perhaps you need to grant access to your inbox to a colleague, because you’re going on vacation but you still need someone to read and respond to important messages on your behalf.
You can do this by appointing delegates. You can specify up to 10 delegates on a personal Gmail account, or 25 for Google Apps for Business, Education, and Government customers. Your delegates won’t be given permission to change your account password or most other account settings, or to use chat on your behalf.
To set up a delegate, use Settings > Accounts and Import tab > Add another account then enter the delegate’s Gmail address and click on Next Step.
In the confirmation dialog, click Send email. The intended delegate will get a verification email explaining that you’ve granted them access to your Gmail account, and inviting them to confirm this request. Once they’ve done so it can take up to 30 minutes for the verification process to complete. In the meantime you can see if the delegate has confirmed access to your account by referring to the Accounts and Import tab under Settings, where the word pending or accepted will appear by the delegate’s Gmail address.
If someone has made you their delegate, you can access their account by clicking on your profile picture or email address in the upper-right corner of the Gmail interface. There you’ll see your colleague(s) listed below your own identity; simply select the identity required and you’ll be able to send or reply to mail from their inbox.
Any messages sent by someone else from your account will have your name listed in addition to the delegate’s name, e.g.:
Phil Ballard (sent by firstname.lastname@example.org)
You can easily remove any delegates when they’re no longer required. Go back into Settings and in the Grant access to your account section, click delete on any account you want to remove.