BG1: I took a break from (online) da
ting to concentrate on myself after my exBF and I broke up over a year ago. Now I'm in a better place personally, as well as having recovered and learned from that rel
ationship. I went back into my inbox on the da
ting site to discover a nice message from Suitor#1, a man that I didn't see myself da
ting (too far away and too old) but was very nice and I figured we could be pen pals at least. Then suitor #2 contacted me. We have hit it off unbelievably well and he lives only about an hour away. We haven't discussed being exclusive yet. Then I was contacted by Suitor #3, who is relatively close but who I am not as interested in. I sent a few messages back and forth to gauge his personality and I don't think we're on the same page. I tried to be open and friendly but he was very awkward, and complained about not having a lot of luck with the whole online da
ting thing. (Gee, I wonder why?

)
BG2: As you may or may not know, there is a phenomenon that happens in da
ting. It happens in real life as well but seems, or at least
feels, more prevalent online. It is called "poofing" - this is when a person just magically disappears. I guess it's like the 'cut direct' except it is usually done to avoid confrontation or the
break up talk. Emails go unanswered, calls unreturned, etc. How annoying and/or hurtful it is depends on how far along things are, and how well you feel it is going. People are divided over the issue. Some chalk it up as par for the course and move on, others consider it cowardly/rude and complain about not getting closure. I can see both sides. I don't like rejection personally, but part of me also appreciates the explanation. I have not enjoyed being poofed, but when things have not been working for me I admit I have usually poofed because I didn't know what to say. This apparent hypocrisy bothers me.

/end BGs
So the situation as it stands is thus: I wouldn't mind staying pen pals with Suitor#1, but he has talked about his desire to get married and asked me for a full body picture - I feel I should tell him I have "chosen" Suitor#2 and let him decide if he wants to remain friends. I feel sorry for Suitor #3, but I also really don't feel the desire to continue talking with him. I really want to be encouraging to him because I understand how hard it is to be a shy or socially awkward person trying to reach out online. I am trying to figure out how to word a message to him that basically says "Sorry I"m not the one for you but keep trying because you obviously have a lot to offer the right person."
So what is the ruling ehellions? I am pretty sure I need to tell S#1. He's extremely good natured so I think he'll take it well. For all I know, he's speaking with a bunch of other ladies and he'll just move on to better prospects.
I don't want to assume, but S#3's complaints about online da
ting and somewhat overly enthusiastic pursuit of me leads me to think he may not have as many options. I am not about to keep in contact with him out of (projected) pity, but I would hate to think my rejection sours him on trying to find someone that makes him happy. So I guess my official etiquette question(s) is/are: Should I tell or poof, is poofing rude, and if I tell how should I word it?

Thank you!
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ETA UPDATE FOR CLARITY:
For the sake of brevity I did not go into detail, but some posts have made it clear I need to break things down a little further:
S#1 contacted me through a da
ting site which I no longer use. I had identified as "seeking a long-term rel
ationship." When he contacted me I made it as clear as I could that my policy is "let's be friends first and see what, if anything, develops." I told him that I was not looking to get married any time soon, and was more interested in cultivating/expanding my social circle. Based on how we have communicated in our emails, I am not 100% sure if he is interested romantically or just a naturally warm and enthusiastic person. Our communication has been infrequent because we are both very busy. He has not expressed any desire to move past email to phone/text/in person.
S#3 contacted me through a different website, the same one on which I met #2. It is not like eHarmony or one of those other sites that focuses on marriage and/or finding "the one." It is a more casual da
ting site with social networking aspects worked into it. When we fill out our profile, we are asked what we are looking for in a rel
ationship. Boxes that can be checked include "new friends," "activity partners," and even "casual scrabble". I checked every box except the scrabble one. S#3 and I have only exchanged 2 or 3 messages at this point, nothing beyond basic pleasantries.
I do not appreciate the presumptive conclusion of some PPs that I am leading these men on. If they bother to read my profile they should be aware of my expectations. I do not open any communication with the language or attitude of "let's start da
ting." I always approach or respond with the cautious attitude of "let's get to know each other better." The idea that I would string men along while I weigh my options is ridiculous, especially since I don't get that many messages or responses to begin with. I am far from the only fish in the sea and I'm sure I"m not the only one they're trying to land.