Strange Google email senders, phishing?

Question

Phishing

Sender examples:

1. [email protected]dar-server.bounces.google.com
   
2. [email protected].com
   
3. [email protected]
   
4. [email protected]endar-server.bounces.google.com
   
5. [email protected].com
   
6. [email protected]tifications.bounces.google.com
   

Has anyone come across this before?

Answer 1

If you look at the senders in the SMTP envelope (in the MTA logs), then these are perfectly normal senders. These are letters sent to the user by an automatic service. A unique sender address is generated for each email sent. This is necessary so that if the letter does not reach the recipient and an undeliverable message (NDR) is returned, it is known exactly which letter and which recipient could not be delivered. NDR is returned to the sender's address, because the address is unique and tied to the sent letter, this allows you to unambiguously match the sent letter and the returned NDR.