Guerrilla Mail is a free disposable email service that has been running since 2006. In this Guerrilla Mail review we test its core features: the ability to send email from a temporary address, scrambled addresses to confuse bots, one-hour inbox retention, and domain blocks that stop certain senders. It remains a capable veteran, but its interface and some limitations show its age. For quick, anonymous signups it still works; for anything needing longer retention or a modern interface, alternatives may suit you better.
What is Guerrilla Mail and how does it work?
Guerrilla Mail is a web-based disposable email service. You visit the site and are immediately given a temporary email address that you can use to receive messages. The address is random, but you can choose from a list of domains. The inbox is accessible without registration, and messages are kept for one hour by default. You can extend the inbox lifetime by clicking a button, but the extension is limited. The service also offers a feature to send email from your temporary address, which is unusual among disposable email providers.
The site has a simple, somewhat dated interface. It shows your temporary address at the top, a list of received messages, and a compose button for sending. There are also options to scramble your address (to avoid bots that harvest email addresses) and to block certain domains from sending to you. The service is free and supported by advertising.
How does Guerrilla Mail's sending feature work?
One of Guerrilla Mail's distinguishing features is the ability to send email from your temporary address. This is not common among disposable email services, which are typically receive-only. To send an email, you click the 'Compose' button, enter the recipient's address, subject, and message body, and send. The recipient will see the email coming from your temporary Guerrilla Mail address.
However, there are limitations. The sending feature is basic: you cannot attach files, and the message may be flagged as spam by the recipient's email provider because it comes from a disposable domain. Also, the sending feature is only available for a limited time—typically the same one-hour window as the inbox. If you need to send multiple emails or have a conversation, you may run out of time. Additionally, some recipients may block emails from disposable domains entirely, so your message may never arrive.
For developers or testers who need to send a quick test email, this feature can be handy. But for any serious communication, it is not reliable. As we note in our guide to sending email from temp mail, disposable addresses are generally not designed for outbound mail, and deliverability is poor.
What are scrambled addresses and why use them?
Guerrilla Mail offers a 'scramble' feature that changes your temporary email address to a new random one. This is useful if you suspect your current address has been harvested by spammers or bots. By scrambling, you get a fresh address without losing access to your inbox—messages sent to the old address will no longer arrive, but you can still see previously received messages.
Scrambling is a quick way to ditch a compromised address. However, it also means you lose any pending verification emails sent to the old address. So use it wisely: if you are waiting for a code, do not scramble until you have received it. Also, scrambling does not delete your inbox; you keep the messages you already have. This feature is similar to what other services call 'change address' or 'new inbox'.
For more on managing disposable addresses, see our best temp mail practices.
How long does Guerrilla Mail keep emails?
By default, Guerrilla Mail keeps emails for one hour. After that, they are deleted from the server and cannot be recovered. You can extend the lifetime of your inbox by clicking the 'Extend' button, which adds another hour, but this can only be done a limited number of times per day. The exact limit is not clearly stated and may change, so do not rely on long-term storage.
One hour is short compared to some other services that offer 24 hours or more. If you need to receive a verification email that might be delayed, or if you want to keep an address for a day, Guerrilla Mail may not be suitable. For a comparison of retention times, see our article on how long temp mail lasts.
Also, note that the inbox is tied to your browser session. If you close the browser or clear cookies, you may lose access to your inbox even within the one-hour window. Guerrilla Mail does not offer accounts, so there is no way to log in from another device.
What are domain blocks and how do they work?
Guerrilla Mail allows you to block emails from specific domains. This is useful if you are receiving spam or unwanted messages from a particular sender. To block a domain, you can add it to your block list in the settings. Once blocked, any email from that domain will be automatically discarded and will not appear in your inbox.
Domain blocks are a blunt instrument: they block all emails from a domain, not just specific senders. So if you block a domain like 'example.com', you will not receive any emails from anyone at that domain. Use this feature carefully, as you might miss legitimate emails. Also, the block list is stored in your browser cookies, so it will be lost if you clear cookies or use a different browser.
This feature is similar to what other services call 'blacklist' or 'filter'. It is a basic but useful tool for reducing spam in your temporary inbox.
Where does Guerrilla Mail show its age?
Guerrilla Mail has been around for nearly two decades, and its age shows in several ways:
- Interface: The design is dated and not mobile-friendly. It works, but it feels clunky compared to modern services.
- Retention: One hour is short; many competitors offer longer.
- No API: Unlike some services, Guerrilla Mail does not offer a public API for developers. This limits automation and integration.
- Security: The site uses HTTP by default (though HTTPS is available), and there have been concerns about privacy. Emails are not encrypted, and anyone with access to your browser session could potentially view your inbox.
- Ads: The free service is ad-supported, and ads can be intrusive.
These issues do not make Guerrilla Mail unusable, but they are worth considering if you need a disposable email service for anything beyond quick, low-risk signups.
When should you use Guerrilla Mail and when not?
Guerrilla Mail is best for:
- Quick signups that require email verification but where you do not want to use your real address.
- Testing email sending from a disposable address (though deliverability is poor).
- Situations where you need a temporary address for a few minutes and do not care about retention.
You should avoid Guerrilla Mail for:
- Receiving important emails that might be delayed.
- Any signup where you need to recover your account later (since the inbox expires).
- Two-factor authentication (codes may expire before you can use them).
- Anything requiring privacy or security (emails are not encrypted).
For a broader discussion of when to use disposable email, see our article on what is a disposable email.
How does Guerrilla Mail compare to other disposable email services?
Guerrilla Mail is one of the oldest disposable email services, but it is not the only one. Here is a quick comparison with typical features of modern services:
| Feature | Guerrilla Mail | Typical modern service |
|---|---|---|
| Inbox retention | 1 hour (extendable) | Up to 24 hours or more |
| Sending email | Yes (limited) | Usually no |
| API | No | Often yes |
| Mobile-friendly | No | Usually yes |
| Custom domains | No | Sometimes |
| Ads | Yes | Sometimes |
As you can see, Guerrilla Mail lags behind in several areas. However, its sending feature is unique and may be useful for specific tasks. If you need a more modern service with longer retention and an API, consider alternatives like MailboxTemp, which offers 60-minute inboxes (extendable) and a public JSON API.
Is Guerrilla Mail safe to use?
Guerrilla Mail is generally safe for low-risk activities, but it has limitations. The service does not use end-to-end encryption, so emails are stored in plain text on their servers. Anyone with access to your browser session (e.g., someone using your computer) could view your inbox. Also, because the service is ad-supported, there is a risk of malicious ads, though we have not seen reports of this.
For a deeper analysis of safety, see our article on is temp mail safe. In short, do not use Guerrilla Mail for sensitive information like passwords, financial details, or personal identification.
Sources
- Guerrilla Mail official website – for features and terms.
- RFC 5321: Simple Mail Transfer Protocol – for how email sending works.
- NIST SP 800-63B: Digital Identity Guidelines – for authentication and verification best practices.
In short
Guerrilla Mail is a veteran disposable email service that still works for quick, anonymous signups. Its sending feature is unique but limited, and its one-hour retention and dated interface show its age. Use it for low-risk, short-term needs, but for anything requiring longer retention, an API, or better security, consider a more modern alternative. Always weigh the risks and avoid using disposable email for critical accounts.