Why are disposable addresses bad for my list?
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Disposable email addresses are one-time-use inboxes. Services like Mailinator, TempMail, Guerrilla Mail, and dozens of others let anyone generate a working email address that expires within minutes or hours. People use them to claim a lead magnet or access a discount without giving their real email address.
Here's why they're a problem for your list:
They expire and bounce. Most disposable addresses stop accepting mail within a day. When you follow up after the initial download, you get a hard bounce. Accumulate enough of them and your bounce rate rises enough to trigger ISP filtering.
They create fake engagement signals. Whoever used the disposable address might open your first email (before the address expires) and then never engage again. This inflates your open rate for one send and then contributes to engagement decay that drags down your sender reputation over time.
Mailbox providers flag them. Disposable domains are well-known. When a pattern of your emails going to recognized throwaway services emerges, that's a signal to spam filters that your acquisition practices might not be consent-based. It's a mild signal, but it adds up alongside other factors.
They indicate the person didn't want your emails. This is the underlying problem. Someone who signs up with a disposable address is explicitly trying not to receive your follow-up communications. You can send to them, but they're not a subscriber. They're a download-and-run.
The fix: validate addresses at signup with a tool that flags known disposable domains. This prevents them from entering your list in the first place. Double opt-in helps too, because it requires someone to access a confirmation email at the address they provided. Disposable addresses can receive that confirmation, but the person's less likely to bother.
Still if you've already got disposable addresses on your list and want to find them, a list clean will flag them by domain. Our cleaning service does this automatically as part of the validation process.
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