Unfortunately, it cannot be increased. The Email Quota refers to the limit on how much disk space your email can take up. Our shared hosting plans have limits set for each plan.
The maximum email quota for the Aspire, Premium, and Pro plan is 1GB respectively while for Deluxe and Supreme it is 2GB and 3GB respectively.
If you require more space, you can purchase any of our independent email services such as Email hosting and Gsuite plans.
N:B- You can only use one email service at a time because of the configuration settings involved.