Why did I get a warning saying I sent a virus?

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Occasionally, you might receive a message claiming that you sent someone a virus. Or you may receive a "bounce" message saying that you sent a message to a nonexistent address, even though you know you didn't send it.

This can be quite alarming — it makes it sound as if your computer, or your account on our servers, is infected with a virus and sending messages without your knowledge. However, this is almost certainly not the case.

Even if you get warnings claiming you sent a virus, the virus was almost certainly sent by someone else with an infected computer, not by you or us.

So why do I get these warning messages?

What you're seeing are erroneous warnings about viruses that forged your e-mail address as the "From" address.

Almost all modern viruses work by scanning the address book and other locations on an infected computer to find a list of e-mail addresses and domain names. Once the virus has a list of addresses, it sends out copies of itself, attempting to hide its true origin by using one of these random addresses as the "From" address of each message.

So if your e-mail address or domain name is stored on someone else's infected computer, that computer may send out viruses that claim to be from you — even though you had nothing to do with it!

While this is annoying, it shouldn't really be a problem. You won't get blamed for it, because every e-mail administrator knows that "From" addresses on viruses are almost always forged and should be ignored.

However, a few companies insist on running software that notifies the supposed "sender" when the system detects a virus. This is a big mistake on their part: as we mentioned, a "sender" address is almost always forged by a virus, so notifying the "sender" just bothers innocent people who had nothing to do with it. You're seeing these mistaken messages.

What can do about it?

In a few cases, viruses will use random forged addresses that don't actually exist — for example, they might use an address like asdfmnbv@example.com. If this is the case, you can avoid seeing warnings sent to these addresses by turning off the catch-all address if you don't need it.

But if you do need the catch-all address, or the viruses are forging addresses that really exist, there isn't much you can do about the occasional false warning here and there. Everyone on the Internet with an e-mail address sees these same warnings, unfortunately.

If you get inundated by virus warnings from the same source, please contact us and let us know the details by forwarding us a copy of the offending messages. We will attempt to block future warnings from that source if possible.