[albertgoeswoof]

Because (according to this announcement) if you don't, Google will put you in the spam folder.

Edit: I suppose it does say "unsubscribe from commercial email in one click". But it's hard to say exactly what they mean. They also don't define Bulk Senders - is that the domain or the sending SMTP server?

[evangow]

They defined bulk senders in the 3rd paragraph: "bulk senders — those who send more than 5,000 messages to Gmail addresses in one day"

[albertgoeswoof]

> is that the domain or the sending SMTP server?

[noAnswer]

Let's hope from what ever comes first, or people will start sending from 1.example.com, 2.example.com ...