From Robert Liu's Blog:
I. In general, legal and finance information should be treated as confidential.
II. Be very careful forwarding internal email to external parties – examine the email trail first and determine if all content is appropriate to share. Once sent externally, emails are impossible to retrieve.
II. When sending email to an alias or distribution list, check the distribution list members you are sending to and know who are in the distribution list before sending email.
III. Whenever possible when responding to emails that requires a definitive answer or a decision response, sync up internally before responding. Imagine if someone outside receives conflicting responses to the same question, it takes longer to clarify and correct.
IV. Remember you are the face of the company for external partners. Lack of consideration in politeness, thoroughness of response, correctness all plays a part in how outsiders perceive the company and the group you work in. Positive impression is an understated value – if you are perceived negatively, you usually don’t know until your manager knows and the whole chain of command at the partner knows.
V. Be more polite than you need to be, especially in email communication where subtle conversation context is limited. Believe it or not, I’ve seen cross company flame wars – not pretty and counter-productive.
VI. Treat all partner confidential information as company confidential. Just a reminder on respecting someone else’s intellectual property.
VII. Be very careful exposing and discussing internal issues with partners – partners should not be expected to solve internal problems. Usually, partners can care less about internal issues; they just need to get the job done. Nice partners may offer to help, but then again, we don’t want to air our dirty laundry – so to speak.
VIII. Cc relevant team members in external communications. Savvy partners sometimes target individuals to search for information they can use.
IX. Don’t delete the email trail both to and from external partners. You never know when you may need the reference. I reference emails from 3 years back still. Long live legacy data.