Server responds like "overquota"

Hi Our email account is not working and saying that server has some issues with storage etc not sure what does it mean. Server responds "Overquota". Please advise. Thanks,

over quota means you have saved more email in the mail account than your provider has allocated. You might need to contact them about what the next move is as if it is full. Actions in Thunderbird beyond emptying the trash may not work as they consume more space before they free space.