Do not use any abbreviation except for "Mr.", "Mrs.", "Ms.", "Jr.", "Sr.", and "c/o". (Military abbreviations are acceptable if too long to fit on the envelope).
Do not use initials in people’s names. Either spell out the whole thing or drop it completely.
You can be formal or informal on your inside envelope.
“and Family” is not appropriate and every attempt should be made to find out the names of the children invited.
“and Guest” is only included on the inside envelope. It is always optional so do not feel obligated to add this to your single guests’ envelopes unless your budget allows.
All names of the states should be spelled out completely.
Only parents are listed on the outer envelope. All children are listed on the inner envelope.
If there are children over 18 still living in the house with their parents, they should get their own invitation.
Think of the outer envelope as just the delivery information. In other words, list only the owners or the main residents. The inner envelope conveys exactly who is invited.
Widows are still considered "Mrs." out of respect for their deceased husbands.
Do not use professional designation such as "Esq.", "M.D.", or "Ph. D." with social stationary. These are only appropriate for business correspondence.
Do not use any symbols such as "#" or "&".
Do not use zip + - it doesn’t look professional.
Numbered streets should be spelled out as well. "23rd Street" should be "Twenty-Third Street". Spell out all parts of the street names: "South" not "S.", "Apartment" not "Apt.", "Street" not "St."
Limit the lines on the outer envelope to 5 and the inner to 3. If it starts to look too crowded, break it up into 2 invitations.
Unless it is absolutely necessary, do not mail your wedding invitations to a work address. Weddings are social events and should be sent to home addresses.