So you've received a message from evite. This, like any invitation, is the start of a social contract. It's someone extending a hand to shake yours or raising a palm to give you a high five. And like a high five offered it is rude to keep your host hanging. Out of respect for your host you should reply. Even if an evite doesn't specify a requirement to RSVP or convey "regrets only" it is courteous to reply, particularly since it only takes a few seconds. Whether you plan to attend or not or aren't sure, your host will appreciate you acknowledging the invitation.
Reply immediately! You are in the invitation already, so it doesn't take much time to make the appropriate clicks to enter a reply. You don't know whether you are going or not? There's a word for that: "Maybe." Are you afraid you won't remember to go back in and change your response once you determine whether or not you are going? Don't worry about it. Most hosts count on about half the maybes to attend. If there needs to be an exact guest count for the event, the host will follow up with you.
You don't want to reply until you think of a witty comment? Really? Unless you have an immediate inspiration, save your wit for Facebook, Twitter, or the party itself. An evite is not a writing competition. The reply is what is important. Oh, and you don't need to include an excuse for a "No" or "Maybe" response.
There is a common misconception that you need to sign up
for an evite account and log in to view/reply to an invitation. Not true! Clicking the link to the message will get you to the
invitation. And yes, the host can see when you've viewed it. Don't let that be a deterent from opening it; instead see that as all the more reason to reply immediately.
Perhaps you are fundamentally against evite. I know I fought it for a while. That doesn't mean you should disrespect your host by ignoring the invitation. Hopefully your host read my previous post and included the key details in the message, so you know what the event is even if you don't want to click the link. Or perhaps you're willing to open the invitation, but you don't want to reply in a public forum. Contact the host via email or other means. Apologize for not using evite, ask for any additional event details, and communicate whether or not you plan to attend.
Unless the host disables or limits the options, evite makes it easy for guests to invite others. Please do this responsibly. Look in the invitation text for indications that additional guests may or may not be welcome. Generally, a casual gathering is more likely to have an open invitation than a formal one. If additional guests are welcome, you typically should not add more than one additional guest per person. That is, if you were invited alone you may add one guest; if you were invited as a couple you may add two guests. This, however, varies greatly by the type of event and the preferences of the host. For example, a host throwing a large fundraising event may truly want you to invite as many people as possible. If you are not absolutely sure, always ask the host. When doing so, you should describe who you intend to invite (e.g. "my cousins from out of town" or "my neighbor, Cheryl, who you met at my birthday party).
There are two ways to add people to an evite. Use the "Total Guests" space in the reply box to add guests who will be attending with you. If you aren't sure if someone will join you, indicate that in the comments. To add guests to the guest list so that they can reply on their own, use the "Invite More" option above the guest list. Be sure to override the default email message with a description of the event, the name of the host, and your name.
If you were added to an evite by one of the original guests you typically should not further extend the invitation. An exception would be the previous example of a fundraiser for which the host is trying to get as many attendees as possible.
You can also use the "Invite More" option to forward the evite to another of your email accounts. This is useful if the evite was sent to a work address and you'd prefer to manage the invitation through your personal account.
Use the functions in the invitation to invite people; Do not forward the email you received from evite! The link in the email you received is tied to your email. When your invited guests click on the link they will be replying as you. If you receive an invitation in this manner, use the "Invite More" option to invite yourself and reply when you receive the new link.
Lastly, update your reply if your plans change. Typically an evite will send a reminder to those who replied "yes," "maybe," or not at all. This is a good opportunity to update your response if necessary. If your plans change the day of you can still update your reply, but you should also contact your host directly.
Bonus tip: Use evite to be a better guest. Some people dislike the lack of privacy when evites use a public guest list; however, you can use this to your advantage. Study the list of probable attendees to review names of people you've met or to to become familiar with the names of new people you may meet. Of course, this isn't helpful if the invitation only shows an email alias like "awesomeguy1," but it will still give you a head start.