It’s quite likely that these are spam. I mean… when’s the last time you used Yahoo!? haha

In most cases, I would recommend a double opt-in process so that people who fill out the form have to click a confirmation link in order to verify that they’re 1) Human, and 2) definitely interested in getting your email. It’s the best way to avoid spam accounts flooding your list, and it’s also a means to ensure people don’t start getting your newsletter “by accident” and then marking you as spam. If you don’t want to require double opt-in for your list, you may want to check the engagement metrics more often so you can prune inactive accounts from the list. There’s no point in having a list of 1000 people if 700 aren’t opening your emails at all. Another thing that even some Big Brands are using is to send out a re-confirmation email once in a while, to folks who don’t have any opens listed in your metrics. A simple “Hi! Do you still want to receive email from me? If so, please click here…” could be a sure-fire way to keep your list in good shape.

My target market is comprised mostly of retired women, and at least half of them have those old email addresses because their husband or kids set it up for them in the 90s and they never left. I only ask for first name, but if I get anyone through ConvertKit’s Creator Network or the Grow plugin, they are not shown the first name field, only the email address field (which may not apply to you). So I would caution not to treat them as spam immediately. I also scrub my list every 3 months by sending a 4-email re-engagement sequence over 2 weeks to any subscriber who has not opened my emails for 30+ days. I end up deleting about 0.5 – 0.75% of my list each quarter (if they aren’t opening they aren’t going to buy). I also have a captcha on my signup page that weeds out bots, and I do not use double opt-in. So if you have good practices in place to keep your list squeaky clean, you don’t need to worry about those email addresses.