Do Gmail and Outlook block .html attachments?

No. Both publish the file types they block, mostly executables and scripts such as .exe, .js and .vbs, and .html is not on those lists. The risk is on the recipient side: many corporate mail gateways flag or silently strip .html attachments, because an HTML file can impersonate a login page or run a script, making it a common phishing tool. You cannot see that filter from your side, so you cannot know in advance whether your file arrives.

What does the recipient experience with each option?

Attachment: it may be flagged by a corporate filter, or arrive as a download with no preview. The recipient has to save the file and know to open it in a browser rather than double-click it as a document. Link: a normal-looking URL in the email body. One click opens a rendered page in the browser, exactly as intended.

Which one lets me know if it was opened?

Only the link. A hosted page can log a view, a timestamp, and (depending on the host) an approximate location and time spent. A file attachment gives you nothing after you hit send, you have no way to know whether it was ever opened.

What about file size or interactivity?

Attachments are capped by the sender and recipient mail servers, often a few megabytes, and any external assets referenced by the HTML (images, fonts, scripts hosted elsewhere) will not load from a local file. A hosted link serves the file as a real page, with all its interactivity, forms, and assets working as designed.

Is there any situation where an attachment is the right call?

Genuinely offline scenarios, sending to someone who will open the file with no internet connection at all, or internal, developer-to-developer handoffs where the recipient explicitly wants the raw source. For anything reaching a client, a prospect, or a non-technical recipient, a link is the safer default.

Guide

HTML link vs email attachment: which one actually works

A link wins on every axis that matters for an HTML file. An .html attachment is not blocked by Gmail or Outlook, but some corporate filters flag or strip it as a phishing precaution, and even when delivered it opens as a local file rather than a page on a server. A link to a hosted version of the same file looks like normal text to a spam filter, opens directly in a browser, can be updated without resending anything, and can be tracked to see whether it was opened. The only case an attachment wins is offline access with no internet connection at all.

The comparison, side by side

Question	Attachment	Link
Passes spam filters	Can be flagged	Yes
Opens as a rendered page	No, downloads	Yes
External assets load correctly	Often broken	Yes
Can tell if it was opened	No	Yes, with the right host
Can be corrected after sending	Requires a resend	Yes, same URL
Works fully offline	Yes	No, needs a connection

Why the attachment loses on delivery specifically

The core issue is not preference. HTML is a favorite phishing format: a file that looks like a document can also be a working fake login form or a redirect. Gmail and Outlook do not block the extension, but corporate gateways often flag or strip it, and the recipient sees a download, not a page. None of this depends on whether your specific file is safe, the filter cannot tell the difference at the point it decides to flag it.

Turning a file into a link takes about the same effort as attaching it

The usual objection to using a link is that it adds a step. In practice, dropping the .html into a host built for this (LiveSend, for example) and copying the returned URL takes under a minute, about the same as locating the file to attach it in the first place. The difference is that one path reaches the recipient as a page and the other as a download.

The short version

Unless the recipient genuinely has no internet access, send a link. It never meets an attachment filter, opens correctly without a download prompt, and lets you know whether it was actually opened.

Ready to turn a file into a link? See the shortest path, no hosting knowledge required.

Frequently asked questions

Do Gmail and Outlook block .html attachments?
No. Both publish the file types they block, mostly executables and scripts such as .exe, .js and .vbs, and .html is not on those lists. The risk is on the recipient side: many corporate mail gateways flag or silently strip .html attachments, because an HTML file can impersonate a login page or run a script, making it a common phishing tool. You cannot see that filter from your side, so you cannot know in advance whether your file arrives.
What does the recipient experience with each option?
Attachment: it may be flagged by a corporate filter, or arrive as a download with no preview. The recipient has to save the file and know to open it in a browser rather than double-click it as a document. Link: a normal-looking URL in the email body. One click opens a rendered page in the browser, exactly as intended.
Which one lets me know if it was opened?
Only the link. A hosted page can log a view, a timestamp, and (depending on the host) an approximate location and time spent. A file attachment gives you nothing after you hit send, you have no way to know whether it was ever opened.
What about file size or interactivity?
Attachments are capped by the sender and recipient mail servers, often a few megabytes, and any external assets referenced by the HTML (images, fonts, scripts hosted elsewhere) will not load from a local file. A hosted link serves the file as a real page, with all its interactivity, forms, and assets working as designed.
Is there any situation where an attachment is the right call?
Genuinely offline scenarios, sending to someone who will open the file with no internet connection at all, or internal, developer-to-developer handoffs where the recipient explicitly wants the raw source. For anything reaching a client, a prospect, or a non-technical recipient, a link is the safer default.

Related guides

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