A person trying to access GreyMail services may experience slower than normal performance when compared to another mail server solution such as Microsoft Exchange
Microsoft Exchange is based on a MAPI proprietary solution, while GreyMail uses a universal IMAP based server.
Slower performance that Microsoft Outlook or other local web client
GreyMail is based on IMAP, which is naturally slow and based off of a different technology than a MAPI based solution. While GreyMail's webmail interface should show mail instantly, you may adjust settings within the webmail to refresh faster, or adjust your settings in your mail client as well.