Cant Create Email Accounts

Hi,

We are using CWP on our Company Mail Server to manage the email accounts of our customers. Currently we have 2624 Email accounts on cwp email section of our domain. 

When we try to create further email accounts, We click Add a New MailBox


A popup windows will show asking to enter mail account name, choose domain and password. On this, the choose domain dropdown is not showing, when checked on chrome console we  see this error.

Also the page is very very slow.

Please advice. and fix this

ERROR MESSAGE

:2083/cwp_fdb7b0eda2d018bf/conektr/?module=email_accounts:1 Unchecked runtime.lastError: The message port closed before a response was received.

Check if you have exhausted your quota or you have a package chosen which limits the number of email accounts go be created