Why Are Email Files so Large?

Email size is determined by much more than just the message

Email on screen
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The average size of an email file is about 75KB. That's around 7,000 words in plain text or about 37.5 pages of typewriting. Unless you or your correspondents happen to be composing novel chapters in email messages, it's other behind-the-scenes factors that make these files so large.

Elements That Affect Email Size

The text of your message is just the tip of the email iceberg. Plenty of other factors contribute to the size of an email:

Formatting. Messages contain formatting information in addition to plain text.

Duplicate message. Rich text emails are often accompanied by a duplicate plain text version of the same message.

Larger email files. Raising the average size of an email file are newsletters and marketing emails, which are often longer and bigger than other emails.

Attachments. Attachments also skew the average. Although some attachments are small, some may be 10MB or larger.

In-message images. Photos, animations, and audio clips all add to email file size. Animated GIFs are particularly large because every frame is essentially an image. The more frames the GIF has, the larger it is.

Headers. Header information that describes the email's route isn't visible, but it counts toward the size.

HTML. If the message uses HTML formatting, that takes up more space.

Quotations. In an email thread that goes back and forth, the same quoted material may appear several times.

Why Size Matters

You don't need to worry about email size if:

  • You have a vast amount of storage space.
  • You don't care how long it takes for your sent emails to load.

However, say you're in business and you market your products by sending promotional emails. Large emails take longer to load and require more bandwidth. Therefore, if you include large graphics, your email may be deleted before the graphics even render. That timeframe may be a matter of seconds, but remember that billions of emails are sent each day, so your marketing efforts have a lot of competition.

Some email clients won't even display a super-lengthy email. For example, Gmail clips emails that are bigger than 102KB. It supplies readers a link if they want to view the complete email, but there's no guarantee your recipient will be willing to click it.

Large attachments and custom fonts are other add-ons that can make an email render slowly. It could be just long enough for the recipient to click away. 

Storage Limits for Email Clients

Most email providers have generous storage policies as well as methods to see how much space your storage allotment has remaining. Still, popular email providers have different size limits, such as those listed below:

  • Gmail accounts receive 15GB of storage space, but that space is shared by Gmail, Google Drive, and other Google services you may be using.
  • Yahoo Mail accounts come with 1TB of storage. Yahoo claims this capacity can accommodate 6,000 years of inbox usage for the average user.
  • Free Outlook.com accounts come with 15GB of email storage.
  • AOL offers 25GB of storage for new messages, 100GB of storage for old messages, and 100GB for sent messages.