How to increase the maximum allowed attachment size in Webmail

Introduction

When changing the maximum allowed attachment size in Webmail, two changes are required to be made. cPanel's internal PHP settings need to be modified, and the maximum message size needs to be increased in Exim.

Procedure

1. Log into WHM as the 'root' user.
2. Navigate to "Home » Server Configuration » Tweak Settings."
3. Select the "PHP" tab.
4. Change the option for "cPanel PHP max POST size (Minimum: 55; Maximum: 2,047)" from "55 MB default" to the textbox and enter the desired value in MB.
5. Click the "Save" button.
6. Navigate to "Home » Service Configuration » Exim Configuration Manager."
7. Select the "Advanced Editor" tab.
8. Scroll down to the "Add additional configuration settings" button.
9. Click the "Add additional configuration settings" button to add a new empty configuration option.
10. Select "message_size_limit" from the dropdown menu of the new configuration option.
11. Enter the desired value in the textbox.
12. Click the "Save" button.

Please keep in mind when making this change that E-mail attachments are encoded using base64 encoding. Base64 encoding typically results in a file attachment size of around 30 percent larger than the original file.