If you’ve checked your mailbox settings in Plesk, you may have noticed a very large number—sometimes 1TB or even 10TB—and wondered what it means.

It’s a common point of confusion, so here’s how it actually works.

What does the 10TB limit mean?

The large number you see in your mailbox settings is not the amount of storage included with your hosting plan.

It’s simply a default placeholder that allows you to set limits for individual email accounts if you choose to. In other words, it’s a flexible setting—not your actual available space.

What is my real storage limit?

Your actual storage is determined by your hosting plan.

This storage is shared across your entire account, including:

• Website files
• Databases
• Email mailboxes

Everything combined must fit within your plan’s total disk space.

How storage is shared

A helpful way to think about this is as a single storage pool.

For example, if your hosting plan includes 20GB of space and your website is using 15GB, that leaves 5GB available for everything else—including all email accounts.

Even if a mailbox is set to “10TB,” it will still be limited by the remaining space in your hosting plan.

Why am I getting a “disk full” error?

This usually happens when your total storage usage (website + databases + email) has reached the limit of your hosting plan.

When that happens, email accounts may stop sending and receiving messages, even if they appear to have plenty of space available in their individual settings.

Should I set mailbox limits?

Yes, we strongly recommend setting reasonable limits for each mailbox.

This helps prevent a single email account from using all available storage and affecting your website or other mailboxes.

It also allows users to receive warnings as their mailbox fills up, rather than running into a sudden service interruption.