Do you know what the email attachment size limit is to the content you put in your email? Several, if not all, email sending service providers restrict how far the email attachment size should go. The limitations are put because of security reasons as well as performance.

For this reason, when considering sending out email notifications or newsletters, you should consider the size of the file attachments and HTML.

Here are some factors you should explore when it comes to email size.

Reasons for Email size limits

There are three primary reasons for putting a limit to emails, they are:

  1. For security. To avoid what is called an email bomb, it is paramount to have a limit to emails. If the content is massive, then there is a high likelihood that the system may go down. Reason being that most emails have limited amounts of ports to back up data.

  2. Large emails may affect the performance of the system. Several email systems cannot process a series of data simultaneously because they use an outdated protocol called an SMTP. The design makes it hard to transfer large masses of data

  3. The content in the email usually is stored in a cloud or a local server. Consequently, it isn't easy to store large volumes of data.

Factors to Consider on Email Size

Know about the email systems of both the sender and the recipient

It is critical to know your limit, but it is also good to understand the recipient's system. Your email system may allow a certain amount of data, but there will be no communication if the recipient can't retrieve the message.

If you do not have information on the recipient's system, then you can follow the general rule, which states that messages should not surpass ten MB

Avoiding the Spam folder

The aim of sending your email is to get to your recipient's main folder and not the spam one. Therefore, to avoid your email from falling on the spam filter, keep it short. An average of 15 Kb to 100 Kb, this way, you will be on the right side of most providers.

Delivery of the content

Delivery of large emails may be in pieces. If your recipient has slow connectivity, there is the potential of cropping your message. Meaning the recipient will receive short clips of the content.

Factors affecting email size (optimization suggestions)

  • Email attachment size limit. Attachments do not affect the email body size but will affect the limit. If a file is too large, one can opt to use links for files stored in the cloud

  • Images. An image can be a logo, a picture of a product, etc. A link will also serve as an excellent way to minimize the email size

  • Codes. It is good to note that messages take up a third of the size of the email.

Take note of any other element you add to the message. Every additional aspect has its effect on the size.

Tips On Keeping The Email Size Compact

If you observe the rules below, you won't have to worry about the delivery or performance of your email.

  • The email body should be within 15 KB to 100 KB

  • Email attachment size limit should be 10 MB. The best way is to use links for documents stored in a cloud server

  • Avoid unnecessary use of images or multimedia

  • Make your emails phone-friendly. Statistics have shown that 42% of people open their emails on mobile devices. The templates you create should be responsive.


If you want your email to get to your recipient without any hitches, the main takeaway is. Keep the email size small. Always cross-check it and test it before hitting that send buttons