We have a group of 25 people who have a common Gmail. Unfortunately, someone is deleting all the new mails. Can someone tell me if we could trace from where the mail are being deleted, please?
It's not possible.
Gmail mailboxes don't have a user detailed activity log. Only the access to the mailbox are recorded in the Last account activity. This could help just in case that the messages were deleted very recently and the users have devices with different IP addresses.
It's worth saying that sharing the account and password of an Google account and signing-in from several devices in certain circumstances could block it. Instead, use Gmail delegation or use a group of Google Groups as a collaborative mailbox. Unfortunately this will not help you to track message deletions either, so you should consider to use another kind of app, like a CRM web app.
As others have said, sharing an email account is fraught with difficulties, and generally isn't a good idea. There are alternatives, though. For incoming mail, you could convert the address to a broadcast mailing list, such that all emails to email@example.com would be sent to everyone who currently accesses the account firstname.lastname@example.org. You could even have a central archive where authorized users could view all incoming mail.
For outgoing mail, you could set each potential sender up with the ability to appear as if they're sending from email@example.com. It might take some creative email client configuration, but it can be done (albeit with some limitations).
It may be innocent. If someone has set a program to download new emails it may be downloading them with the POP protocol
Try changing the password and then asking everyone to check-in or turn off support for POP protocol
Status: POP is enabled for all mail
When messages are accessed with POP DELETE EMAIL IN GMAIL