Could one malicious email attachment contaminate all attachments in my cloud email account? There are various preview functionalities available in Gmail or Microsoft Outlook that would effectively interpret attachments like images or PDFs on the server. There must be some protection in place, right?

  • Sorry for a vague question. I am speaking of the major email services like gmail or outlook. Suppose I received one malicious email, previewed, downloaded and opened it. That could compromise my pc. Could said actions infect any other used to be known-good files in my account on the mail server? If I delete the malicious email and continue to work with the files from that account from another clean pc, would that be safe? One malicious attachment should not alter any other files on the mail server unless there is a serious flaw in its architecture, right?
    – aleks1265
    Commented Jan 11, 2022 at 13:42

1 Answer 1


What you are suggesting could happen, but it would not be contained to just your account. As you say, it would require a server-side vulnerability to be exploited to get the server to behave in a malicious way. Everything the server touches would then be compromised. Your personal mailbox would be the least of your worries.

However, the "preview" function happens locally and not on the server.

So, sure, vulnerabilities on the server might occur, but major services have been doing this for decades and know how to protect themselves from these exploit and how to recover safely.

  • Thank you for your answer! May I build on the original question. So far I had an understanding that if I preview documents in Gmail or Google Drive then the interpretation of documents happens on the server and I get a "safe" remotely rendered image in my browser. That means I was wrong, and, generally speaking, if an attachment targets a specific vulnerability in my browser my pc might get compromised by merely previewing attachments? Sometimes the preview happens automatically.
    – aleks1265
    Commented Jan 11, 2022 at 15:39
  • Yes, preview could exploit a vulnerability in your browser. We have quite a few questions here about that. It falls under the "possible but not likely" category.
    – schroeder
    Commented Jan 11, 2022 at 15:43

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