Gmail 552 5.7.0: content presents a potential security issue
Gmail blocked the message because something in it, usually an attachment type, a macro document or an encrypted archive, could carry malware. The message wasn't delivered.
552 5.7.0 This message was blocked because its content presents a potential security issue.
Start of Gmail's text for 552 5.7.0, as listed in Google's SMTP errors reference (the published line goes on to point to its blocked file types page).
What 552 5.7.0 means
Google's SMTP reference lists 552 5.7.0 "This message was blocked because its content presents a potential security issue" and links to its page on file types blocked in Gmail. That page explains that Gmail blocks messages that may spread viruses, such as messages that include executable files or certain links.
Google lists what it doesn't allow: certain file types, including in compressed form (like .gz or .bz2) or inside archives (like .zip or .tgz); documents with malicious macros; and password-protected archives with archived content. The blocked types include .exe, .bat, .cmd, .js, .jar, .msi, .ps1, .scr, .vbs, .iso, .img, .lnk and many others, and Google says it updates the list often. A message can also be blocked without any attachment when its content, images or links might share viruses.
Renaming a file to dodge the check isn't a fix and looks like the behavior of malware. If the file is legitimate, Google's suggestion is to share it through Google Drive or another file-sharing link instead.
Likely causes
- An attachment of a blocked type, such as .exe, .js, .iso or .lnk, including inside a .zip.
- A password-protected archive that Gmail can't scan.
- An Office document with macros that Gmail considers malicious.
- Links or content in the message that Gmail associates with malware.
How to fix it
If you sent the message
- Share the file through Google Drive or another file-sharing link instead of attaching it.
- Don't zip, encrypt or rename executables to get past the check.
- If you didn't send an attachment, check the links in your message and your signature, and scan your computer.
If you're the recipient or their admin
- Ask the sender to share the file through a link; Gmail doesn't let users receive blocked file types as attachments.
Frequently asked questions
How do I send an .exe or a script file to a Gmail user?
Upload it to Google Drive or another file-sharing service and send the link. Gmail blocks those file types as attachments, even inside a zip, and Google suggests sharing through Drive instead.
Why was my message blocked as a security issue with no attachment?
Google says messages can be blocked without attachments when the content, images or links might share viruses. Check every link, including in your signature, and remove any that point to file downloads you don't control.
Sources
- Gmail SMTP errors and codes (Google Workspace Admin Help)
- File types blocked in Gmail (Gmail Help)
- RFC 3463: Enhanced Mail System Status Codes
Provider messages are quoted as the provider publishes them. Servers can change their wording, so the bounce you received may differ slightly.
Related codes
- 554 SMTP 554: transaction failed
- 554 5.6.0 554 5.6.0: email message is malformed, not accepted
- 552 5.3.4 552 5.3.4: message too big for system
- 530 5.7.0 530 5.7.0: authentication required (or STARTTLS first)
- 550 5.7.1 Gmail 550 5.7.1: message is not RFC 5322 compliant
- 550 5.7.1 Gmail 550 5.7.1: the IP you're using to send email is not authorized
- 553 5.1.7 553 5.1.7: the sender address is not a valid RFC 5321 address
Related guides
Which email attachment types are dangerous, and what should you block?
Which email attachment types are dangerous, from .exe and scripts to macros, HTML, SVG, ISO and OneNote files, and which to block outright versus quarantine.
9 min read Phishing & threatsPassword-protected ZIP attachments: why they're risky and how to handle them
Why attackers send encrypted ZIP, 7z and RAR files with the password in the email, how containers dodge Mark of the Web, and how to quarantine them.
9 min read Phishing & threatsWhy does Office block macros in files from the internet?
Why Office blocks VBA macros in files from the internet, what the SECURITY RISK banner means, how Mark of the Web works, and how admins allow trusted macros safely.
9 min read Setup guidesHow do you set up advanced phishing and malware protection in Google Workspace?
What each Gmail Safety setting in Google Workspace does, how warning, spam and quarantine actions affect users, and which editions get Security Sandbox.
10 min read