Some clients using Outlook and other email applications (not browser access) have really slow response and it takes a long time to open their account. Are there any typical problems to look for?
One of the major problems I see is the amount of mail in their inbox. Having many, many folders is also a problem. I have seen Inboxes with over 10K emails. This will cause a significant slowdown both when first starting Outlook or when synchronizing the send/receive feature.
I have to ask "What in the world do they do with 10K emails in the Inbox?" How do you find things. The first thing the email application does when it starts up it to synchronize the folders. Usually the Inbox is first. So to insure you see all your new mail and it is showing with the Read/UnRead indication, there is a lot of work that needs to take place. Remember you may have accessed your mail via your smartphone or other computer. So the email application must sort through everything to make sure what you have is the correct version of your mail. So it takes a long time especially over the Internet connection.
If you use a browser to access your mail, it only needs to look at the first page of data for the Inbox.
Think of your email as a filing cabinet. You always mark the cabinet drawers so you can make it easier to find things. The same thing applies to email. Sort your mail into folders that make sense to you. Then move the mail to those folders. Minimize the amount of mail that is in your inbox. And organize the mail by folders.