Email Attachment Size Limitations

Our email system prohibits the sending or receiving of emails exceeding 50 megabytes (50MB).

However, you cannot send an email with a 45-50MB attachment. Why? To understand this limit, there are a few important things to note:

• The first and most important overall thing to know is that email was never designed for the transmission or storage of files. The email protocol was originally designed as a text-only communication method, and the ability to attach files to internet emails didn't come about until over a decade later. This fact ties directly into the next point.
• The limit is for the size of the overall email, not the size of the attachment itself. Without getting overly technical, in order to add an attachment to an email, it has to be encoded in a particular way--taking data that wasn't designed to be in an email and converting it into characters that can be transmitted via the email protocol. This encoding process results in a "bloat" of the file's size, typically adding over 30% of the original file's size. For example, adding a 1MB file attachment and sending it with very little text in the message body of the email will result in an overall email size of approximately 1.37MB after encoding. It is this size that email servers are looking at. Because of this bloat, we recommend trying to limit any file attachments to a total size of 35MB or less.
• Other organizations may have smaller limits, some may have larger. Each organization sets their limits based on whatever makes the most sense for their environment. We've increased the outbound message size limit a few times over the years, and when going over 50MB we started having more issues delivering emails to other organizations who could not accept mail larger than 50MB, so that's how we landed on our current limitation.

As file sizes increase, it's increasingly advised to not use email for transmitting files to users. Did you know you can share files directly from OneDrive? You can find instructions for that by clicking HERE!