Magpie Tech Tips

November 01, 2013

Why Does My Company Limit Email Attachment Size?

Why do we still have a max size limit on email attachments? 10MB, 25MB, even 100MB attachment sizes aren't enough! However, good reasons for size limits do exist. As do better options for sharing large files.

Are you stuck with an attachment size limit (10MB, 50MB) on your work emails? Frustrating as it is, there IS a reason for such establishing max email attachment sizes. Several in fact. By the time you finish reading this, you'll understand why the size limit's in place.

The Security Reason

Mail servers are still computers. Overwork them and they eventually crash. One surefire way to overwork a mail server is to keep sending emails with huge files attached, over and over. Cybercriminals know this. They've used this very tactic for years.

Why? Sometimes just to enjoy the destruction. Other times they slip malware into the network amid crashing the mail server. Either way, this is a major reason for keeping email attachment sizes low.

The 'Guaranteed Arrival' Reason

Another reason IT departments limit attachment sizes has to do with the Web. While the software running mail servers continues to advance, you have zero guarantee another mail server out there can understand how to accept larger files. It may be older, out of date, or have extra security running.

Let's say you have two mail servers, Server A and Server B. Server A belongs to your business, and has no email attachment size limit. Server B belongs to one of your customers, and has a 10MB email attachment size limit.

One of your users sends the customer an email with a 50MB file attached. Server B rejects it automatically. You didn't know that Server B had the limit beforehand, but now you do.

This is why many IT departments limit email attachment sizes. There's no way to know which mail servers impose attachment size limits or not. To maximize the chances of your emails arriving—ALL your emails—they set a low size limit.

Judging by current cloud & storage trends, this limit's slowly going up worldwide. It's still better to err on the side of caution though.

The File Storage Reason

Finally, a mail server isn't a file server. You use file servers to store files; mail servers store mail. However, many office users will treat a mail server like a file server, by sending all their files via email. It's common, yes, but not advisable.

This is why it makes sense to keep a limit on email attachments. If you can't send a large file via email, you have to use a better storage/sharing medium. Those exist—plenty of them in fact. We'll list a few options below.

Need to Send Large Files? Use a File Sharing Service Instead of Email (They Work Together)

Instead of sending large files over email, use a file storage/sharing system. Many exist, from Dropbox to SharePoint. These are a few we recommend:


**Updated August 2019