It's late, their name is sitting at the top of a thread you haven't touched in months, and you've written something. Maybe "hey, you crossed my mind today." Maybe a whole paragraph. Your thumb is over send and your heart is doing the thing. You still care about this person. That part is real, and there's nothing wrong with it. The question is what to do with it, and most of getting this right happens before you type a single word.
Here's the question to sit with first, and to answer truthfully, which is harder than it sounds: what do you really want from this? Not the polite version. The real one. Do you want them back? To be friends? Closure, whatever that means? Or do you, if you're being honest, just want to feel less alone tonight, and they're the person your loneliness happens to have a phone number for? Because the message you should send, or whether you should send one at all, depends entirely on which of those it is. And the person on the other end can almost always feel the difference, even when you've hidden it from yourself.
That last one is where reach-outs go wrong. You tell yourself it's a casual "just checking in," but underneath it's a bid, for reassurance, for a door to reopen. The recipient feels the weight of the hidden ask even though the words are light, and now your breezy little text has put them in a corner: answer warmly and risk leading you on, or stay distant and feel cruel. You didn't mean to do that. But a message with a secret agenda always lands heavier than the words on the screen.
So the first kindness, to both of you, is to know your own motive before you send. If the real answer is "I ache tonight and want them to make it stop," that's a true feeling, and it's also not theirs to fix, and the message that asks them to is the one you'll regret by morning. I've sent that version. The 1am one. It has never once gone the way I hoped.
If, in daylight, you still want to reach out, and your motive is something you'd be willing to say out loud, then keep it simple and make it weightless.
Send one genuine thread, not a vague hello and not a flood. "Hey, I walked past that ramen place we used to go to and thought of you. Hope you're doing well." That's a real, specific reason you thought of them, offered with no hook in it. Compare it to "hey stranger," which signals nothing, or the long retrospective on the whole relationship, which signals everything and demands a matching reply. The good version gives them something warm to receive and an easy way to answer, or not.
And attach no expectation. This is the hard part. Send it as a gift, not a transaction. They might reply in an hour. They might reply in a week. They might not reply at all, and that is information too, and it is allowed. The second you send it needing a particular response, you've handed them your peace to manage, and you've turned a kind gesture back into the bid you were trying to avoid.
One thing worth saying plainly, because it sends a lot of these texts: closure is mostly a story we tell ourselves to make reaching out feel justified. The clean conversation where they finally explain everything and you both walk away at peace rarely happens, and when it does, it usually doesn't come from a text. If what you want is closure, it's worth asking whether a message is really the route, or whether you're using the word to give yourself permission to make contact. Sometimes it really is closure. Often it's the loneliness wearing a more respectable coat.
Caring about an ex isn't a problem to solve. It's just a thing that's true, and it can stay true quietly, without a text attached. But if you do reach out, reach out clean: knowing what you want, asking nothing of them, willing to hear silence. That's the version that respects both of you, and it's also, for what it's worth, the one most likely to be welcomed, precisely because it isn't asking to be.
Know why you're sending it, and make it something real. Then let it go, whatever they do with it.