I'm asking on behalf of a friend.
A few days ago, I received a email with his full name (with no subject), thought that's from him. But when I opened it, there was only an obvious spam link, and I saw that not only I received this mail but also 20 other of his contacts, however when I checked the address from which this mail was sent, I saw that the mail was NOT his own yahoo mail address , but instead a mail address on a spam domain which contained his name. and I received not only one of these emails, but many, and each time they were sent from a different address and with a different spam link in it.
He can still sign in to his yahoo mail, so his password was not changed.
Has someone access to his mail account or could it also be a dangerous virus on his computer and/or android phone? (he has the yahoo app on his phone)
Which steps should he take?