There are some words that you just have to hear in context to know the correct punctuation. Such is the case with the word again.
If the word again begins a sentence, it is a conjunctive adverb, and it has a comma after it.
...Again, I need to ask you to wait until I finish my question.
...We called late in the day; again, we were told he was not in.
When the word again comes in the middle of a sentence, it is either an adverb, in which
case it takes no punctuation, or it is a parenthetical, and it takes commas around it. The
only way to tell is my intonation.
If it is included in the sentence with no pause or change in tone, it is an adverb. If it is
said with pauses around it and a change in the timbre of the voice, it takes commas
around it. (And there is really no way for me to indicate this here in print.)
...We were again reminded of the fragility of life. (No pause, no change in voice)
...We were, again, reminded of the fragility of life. (Pause on either side, change in voice)
After the word and, again needs two commas or no commas. A comma on either side of
it is not correct.
...And again, I want to emphasize this. (It is just wrong!)
...And, again I want to emphasize this. (Wrong again!)
...And again I want to emphasize this.
...And, again, I want to emphasize this.
Happy punctuating!
Margie