Can't adjust mailbox size limit

[SDshooter]

I have a user who filled his mailbox within days. (Not sure why the mails aren't deleting when he does a POP3 check.) I tried to adjust his mailbox size from the default 100MB to 1000MB, but Plesk is giving me a "Incorrect limit value was specified" error when I change the default to any custom setting. WHY?? There is plenty of space available.

 

[EdwardDekker]

You have to change your service plan and use a add-on to allow 1000 mb mailbox to this domain.

1. Service Plan -->> Add new Add-on -->> Recources and add extra space to the mailbox.
2. Go to Subscriptions -->> select Domain -->> change plan -->> select "Add-ons".
3. Now you be able to change the size of the mailbox.

That's all.