Does Gmail block certain emails?

Last reviewed: September 28, 2026 · Markdown version

Yes, and "blocked" covers four different outcomes: some messages are refused for security reasons, some bounce back to the sender, many more are delivered but put in Spam, and the ones you block yourself also go to Spam. Which one happened decides where to look. A refused or bounced message never reaches your mailbox at all; a spammed or self-blocked one is sitting in your Spam folder.

1. Refused: content that may carry a virus

Google's page on this starts with the error people see, "This message was blocked because its content presents a potential security issue", and says "Gmail blocks messages that may spread viruses, like messages that include executable files or certain links." Beyond the long list of file types, it names two cases people rarely expect: "Documents with malicious macros" and "Password-protected archives with archived content". It also says a message with no attachment at all can be blocked: "This can happen when you include content, images, or links that might share viruses." (File types blocked in Gmail, read 28 September 2026). The full file-type list, and why zipping does not get around it, is on why Gmail attachments keep failing; the virus scanner is on are Gmail attachments secure?

2. Bounced: the sender gets it back

When Gmail cannot deliver, the sender receives a message from "Mail Delivery Subsystem" explaining why. Google's bounce page lists the usual reasons, among them "Your email is flagged as spam or temporarily rejected", sending limits, and "The recipient’s inbox is out of storage space" (Fix bounced or rejected emails, read 28 September 2026). Three matter most when you are the one not receiving:

Your storage is full. The bounce page: "Your recipient is out of Google storage and can’t receive new messages." If nothing at all is arriving, check this first; what to do about it.
You are getting mail too fast. Senders may see "The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered." Google's advice to them is to reach you another way (Limits for sending & getting mail, read 28 September 2026). That page does not publish the rate.
The sender's own setup. Google's rules for anyone sending to Gmail require SPF or DKIM authentication, and say messages without it "might be marked as spam or rejected with a 5.7.26 error" (Email sender guidelines, read 28 September 2026). If one company's mail never arrives while everything else does, this is a likely cause, and only the company can fix it.

3. Delivered, but to Spam

Most of what people call blocking is this. Gmail files suspected spam automatically, and each message in Spam carries "a warning at the top of each email that explains why Gmail sent it to Spam": a spoofed address, suspected phishing, an unconfirmed sender, and others (Report spam in Gmail, read 28 September 2026). On a work or school account there is one more: "your admin might set controls to mark certain emails as spam", and only the admin can change that. Rescuing a message is Not spam; after that, future mail from the sender stays out of Spam. How the Spam folder works.

4. Blocked by you

When you block a sender, Gmail does not refuse the mail: "After you block the sender, all future emails from them go to Spam" (Block or unblock an email address in Gmail, read 28 September 2026). The block page describes what you see, and it does not say whether the sender is told; we have no source that says they are, so we will not claim either way. The list of senders you have blocked is under Settings, Filters and Blocked Addresses. How blocking works in detail.

Finding a message that never came

Search All Mail and Spam for the sender's address.
Check your storage; if it is full, that is the answer.
Check Filters and Blocked Addresses for a block or a filter that deletes it.
Ask the sender for the bounce message. Its wording tells you which of the cases above applies.

That order is ours: it goes from the checks you can do alone to the one that needs the sender.