What does this mean?

[KissMeKate]

<p>I tried to email something, but then this came back immediately: </p>

<p>

Your message cannot be delivered to the following recipients:</p>

<p>Recipient address: [some email address]
Original address: [the address i was emailing]
Reason: Over quota

</p>

<p>Does this mean that my email account is over quota or the account that I was trying to email was over quota? According to my account I still have tons of storage left. Thanks.</p>

[system]

<p>THeir email over qutoa.</p>