Email and spam folder issues

Is there any actual way to stop my emails from landing straight in someone's SPAM folder? We run some vacation rentals, and we handle all our inquiries through our email—specifically the one provided by AT&T. We reply to everyone, but more often than not, we end up hearing nothing back. For the longest time, I just assumed people were losing interest or booking elsewhere. But lately, it’s become a pattern: these persistent folks will follow up or call us directly, and when we tell them we already sent a reply, they swear they never received anything. It’s only after we suggest checking their junk folder that they realize our message was sitting right there the whole time.

The reality is that most people don't even bother looking at their SPAM folder, which is costing us a significant amount of business. The exact same thing happened yesterday; we replied to an inquiry, and then this guy calls me this morning asking if we're still interested because, of course, my email went straight to his spam. I need to find a way to put an end to this once and for all.

Should we be switching to a different email provider? Right now, we're just using the standard stuff from AT&T (something@provider.com).

I suspect the issue might be that our correspondence is almost always identical in structure. We list our properties on several major travel sites where guests can send inquiries directly. They fill out a form, the system generates an email that hits our inbox, and the subject lines are always virtually identical (usually something like "Booking Inquiry: Arrival Date - Departure Date"). We then reply to those, so every subsequent email looks like "RE: Booking Inquiry: Arrival Date - Departure Date." Since the content and titles are so repetitive, I wonder if spam filters are flagging us for it. Surely there has to be a solution to this.

Try using Gmail... those messages don't end up in spam.

Look, let's be real: the person sending the email doesn't have much say in how a recipient's spam filters—or their entire mail provider—decide to flag things.

It honestly doesn't matter which service you're using to hit send. Even if you're blasting them from a Gmail account, it's all the same.

@User1: I was actually a bit worried about this myself. So, you're telling me there isn't really a fix for this issue?

As a fallback plan, what I can do is reach out to all the platforms where we run our ads. I'll suggest that, for everyone's own sake—both theirs and ours—they should include a note on their website. Basically, once a customer submits an inquiry, the confirmation message should explicitly tell them to check their spam folders immediately.

And eventually, maybe instead of just hitting reply to the notification email, I could just manually copy the customer's email address and send them a direct message from my end. My thinking is that it shouldn't trigger any spam filters that way, since it would be a genuine first contact from me. It’ll just be a standard, plain-text message without any suspicious links or those canned, generic templates. I realized I forgot to mention this in my initial post, but the automated notifications we get from these sites actually contain links back to the advertising platforms themselves, which probably doesn't help matters.