Although efficient, emailing your client can be hazardous to the attorney-client privilege, unless you are very conscientious. Some cautions:
If you represent an individual, don’t send emails to your client’s place of business, as there may be a lowered expectation of privacy compared with a private email address. Any emails you send there may be discoverable.
In some instances, a husband and wife share one email address. If you send emails to a shared email address, you can run into potential waiver issues, because a non-client has access to privileged emails. Avoid any such issues by asking your client to create a separate individual email account for your communications.
Think twice before copying anyone on an email to your client. Copying your paralegal, secretary, or co-counsel does not create a waiver issue. But if you copy your expert witness or someone else outside your firm, you are looking for trouble. The same caveats apply if you copy your client on any email you send to anyone not covered by attorney-client privilege or work-product doctrine. The better practice is to forward emails to your client as appropriate.