Once you have configured the account on an email program you have several options. These will depend on the program you use. I will just discuss a few common ones.
Leave Copy on Server. If you check your business email at home you might want to leave a copy on the server. That way when you go into your office, you can download the same emails. Perhaps you want to check stuff at home, but you need to print out a copy of the customer's email for their file which is at your office. Another situation might be if you use a PC and a laptop. You might want to check emails on the laptop from time to time, but you need it to stay on the PC in order to print the email or copy information into your Customer Management system.
Signature. You can create a signature for your outgoing emails. In that way your phone number, web site, or company name will show at the bottom of all your emails. You will not have to remember to include this information every time. Remember to include it for all emails including responses.
Stationery. I would skip this. It creates a small attachment to your email. Some networks do not allow people to open any emails with attachments.
Automatically Add Addresses. Instead of remembering to add people to your Address Book the Email Program can automatically add anyone you respond to. This is a great time saver but has one huge downside. Several year's ago, I received a Worm at work from someone at another company. I received this simply because I was listed in their address book. While I believe the Email Programs are better at preventing this now, it is still a risk to be aware of.
Automatic Send/Receive. I know of situations where people have 'sent' urgent emails to customers. Unfortunately, they forgot to click on Send/Receive, and the customer did not get the email till weeks later. The options vary with each program but you should at least have it send all mail when you exit the program.