Do you want to allow and enable other Gmail users login into your Gmail email account? This is possible using (now free) ‘delegation’ feature in your Gmail account. Delegation feature allows you to setup upto 10 users to login, read, write and delete email message from specific (same) Gmail email account.
Setup ‘delegation’ feature in Gmail
1. After Gmail login, goto Settings link at top right.
2. Then goto “Accounts and Import tab” and look for ‘Grant access to your account’.
3. Click “Add another account” and the type Gmail email ID of users for granting access.
4. Users whose email ID you enter for access will receive confirmation email. After successful confirmation, added users can access specific Gmail account content.
5. To login, read, write, delete emails of common email account, just login into your Gmail account and then switch to common email account from top right part of Gmail email screen.
Also, when you send email messages from common account, it will also mention your original email ID as “Sent By”. You can setup upto 10 users to access specific same Gmail email account. [via Gmail Blog]