It is still effective if you have a quality email list. Let send newsletter or promotions to your list and make sure that your subscribers want to buy or concern about what you offered in your email then
As Marc says, you need a good email list otherwise it doesn't work too well. Email marketing can use different approaches. I tried sending cold emails for a long time but found for the most part it was just a total waste of time.
Before start doing anything with your LinkedIn or email or anything, please make sure that you know who is your buyer persona or the ideal customer profile. Otherwise, all your further efforts would be converted to spam.
Also, don’t forget to optimize your LinkedIn Profile before you start your outbound campaign.
Email marketing is always effective if your approach is right. The customers nowadays are moving to the world of online that creates the door for the marketer. Try to manage a quality email list and make engagement with your potential customers.
Email marketing is up to 40 times more effective than social media, according to a study done by McKinsey & Company. The same study also shows that the buying process happens 3 times faster than on social media.