Gmail announced yesterday that the email size limit has been upped from 25 MB to 50 MB, but there’s a catch — it’s only for RECEIVING emails. Meaning, if you’re a Gmail or G Suite user, you are still limited to sending an email with a max of 25 MB of content, but if a NON Gmail user sends YOU an email, that email can contain 50 MB of data. That data can be anything from inline images to attachments to even 50 MB worth of HTML, although that would be a heck of a lot of HTML.

Yesterday tech blogs were quick to cover the Gmail announcement, but most of them did so incorrectly, including PC Magazine and ubergizmo, both of whom incorrectly referenced the limit as an attachment size limit instead of an overall email size limit. Even the venerable TechCrunch failed to emphasize that the limit is for RECEIVING only. Having built GMass, which is a plugin for Gmail that adds mass email and mail merge capabilities to any Gmail or G Suite account, I’ve become an expert on Gmail, so you can count on me and my blog for accurate and detailed information.

GMass enforces an overall email size limit of 12 MB. Why do we do this when Gmail has a 25 MB size limit? Because while it’s fine to send large attachments for person-to-person email, sending large attachments in mass clogs networks and frustrates recipients.

Assume for a moment that you are sending a mail merge campaign in Gmail to 1,000 recipients, and each contains a 20 MB attachment. That’s 20 Gigabytes of data sent across the Internet, an astronomical amount for a 1,000 recipient email campaign. Even with our current limit of 12 MB, you can easily saturate a network, so please use attachments sparingly in email, and be aware that the size of an attachment can double when its encoded into the format necessary to transmit over email. Meaning, if you attach a 5 MB file to an email campaign, that 5 MB will expand to about 10 MB after it is base-64 encoded and put into MIME format.

Ajay Goel

Ajay is the founder of GMass and has been developing email sending software for 20 years.