Yes, it is theoretically feasible to spread malicious links or induce the download of malicious files by manipulating the automatic reply function of the mail system, but the actual attack is more difficult and depends on specific conditions. The following are detailed analysis and prevention recommendations： --- ###**Attack principle and feasibility** 1. **Automated response to exploit** -If the automatic reply function of the mail system (such as Exchange, Sendmail, etc.) (such as "Holiday automatic reply") does not strictly filter the content, an attacker may use forged sender addresses or specific trigger words to lure the system to automatically reply to emails containing malicious links. -For example: an attacker sends an email with `<img src="恶意链接">, and the automatic reply may include it in the reply content. 2. **Social engineering induction** -By pretending to be a system notification (such as "Your mailbox is full, please click the link to clean up"), induce users to click on the link in the automatic reply or download the attachment. 3. **Mail server configuration defect** -Open Relay or weakly authenticated SMTP servers may be abused to send forged automatic reply emails. --- ###**Technical limitations and difficulties** -**Content filtering mechanism**: Modern mail systems (such as Office 365 and Gmail) usually automatically scan links and attachments to intercept known malicious content. -**Header forgery detection**: Protocols such as SPF, DKIM, DMARC, etc. will verify the authenticity of the sender and reduce the success rate of forged automatic replies. -**User vigilance**: Users have low trust in automatic reply emails, and the attack effect is limited. --- ###**Real cases and attack scenarios** -**Phishing email + automatic reply combination** The attacker sends emails that trigger automatic replies in batches (such as "meeting request" in the subject) and inserts malicious links in the replies. If the automatic reply function of the enterprise mailbox is not turned off, a chain of transmission may form. -**Malicious rule injection** By invading the user's mailbox (such as stealing credentials), setting malicious receiving rules (Rules), and automatically replying to specific emails with malicious files. --- ###**Preventive measures** 1. **Corporate administrator** -Disable unnecessary automatic reply functions, or restrict them to only take effect for internal domain names. -Enable email content filtering (such as URL reputation in scanned links, attachment sandbox detection). -Force SPF/DKIM/DMARC to be enabled to prevent forgery by the sender. 2. **Ordinary users** -Be wary of links or attachments in automatic reply emails, especially from unfamiliar senders. -Manually turn off the automatic reply function of the mailbox (such as vacation reply). - Report suspicious emails to the IT department. 3. **Technical defense** - Use Advanced threat protection (ATP) solutions to detect abnormal email behavior. -Regularly audit mailbox rules to prevent malicious rule injection. --- ###**Conclusion** Although such attacks may be achieved under certain conditions, the actual risk is low. **Core defense depends on the security configuration of the mail system and user security awareness**. Enterprises should prioritize turning off high-risk functions and deploying multi-layer protection mechanisms.