Found these in my inbox. Thought they were pretty good so decided to post them. - BL
Use meaningful subject lines. Using a subject line of "Howdy" (we all do it... but shouldn't) makes it hard for people to browse their e-mail inbox for specific e-mails - e.g. the one that should have been titled "Directions to Jeff and Abby's house".
Break up major topics into separate emails. This relates to the prior point. If an long e-mail about the weather, politics, Aunt Bessie's arthritis, etc. has buried in it some really important medical information....that makes it hard to find that important information amidst the routine. Better to break that into two emails - one called "Family News" and another titled "Important Medical Information". This also prevents people accidently deleting the information that should be saved.
Use email priority settings appropriately. Not every email application supports this but most allow you to flag your outgoing email as "Routine" versus "Important" or something like that. This is handy because when the email lands in someone else's inbox it will have a flag or indicator (e.g. an exclamation mark) that helps them know this is an important email. Don't mark everything as important - people will ignore you after awhile. If your email tool doesn't support setting the priority of outbound email (or it is too hard to use), try indicating this in the subject line - e.g. "Travel Info for Trip to France (Important)" or "Parent-Aide Handbook (Please save)".
Be cautious about putting too many addresses on an email. When you put many (how many?) addresses on an email, many email systems will think it is spam. To get around this, consider sending an email to groups of people separately - i.e. send it first to family but then forward it to selected friends. 5 addresses is fine. 55 is almost always a problem. 25? Depends on the servers that handle that email. That breaks some rules of e-mail etiquette (it is impolite to send things "blind copy" or "behind some's back") but is practically necessary with spam filters working as they do.
Edit emails before you forward them. If you forward an email that has already been forwarded many times, it can also get flagged as spam and may never reach your recipients. To get around this, try editing/pruning the email before you forward to cut out all that extra text shown as it was forwarded before and leave just the text/message/etc. that is important.