Your best bet is to use POP3 instead of IMAP, as this will store all email on your computer rather than on the server.
Another option would be to use the archive feature, as that would remove older emails from your server and keep them in your local folders, thus freeing up space on the server.
Thanks Gary - how do I switch from IMAP to POP3?
You will need to create a new account.
See the help file here and follow instructions for POP3 (starts at Setting up particular email addresses )
So that link did not work, sorry.
[http://www.emclient.com/webdocumentation/en/7.0/eMClient/Default.htm#Accounts/Create New Account.htm](http://www.emclient.com/webdocumentation/en/7.0/eMClient/Default.htm#Accounts/Create New Account.htm “Link http//wwwemclientcom/webdocumentation/en/70/eMClient/DefaulthtmAccounts/Create”)