don't include ".PEEK" in fetch keys, only in command where applicable

lib/imap.js

@@ -925,7 +925,7 @@ ImapConnection.prototype._fetch = function(which, uids, options, what, cb) {
     uids = [uids];
   utils.validateUIDList(uids);
 
-  var toFetch = '', prefix, extensions, self = this,
+  var toFetch = '', prefix = ' BODY[', extensions, self = this,
       parse = true, headers, key, stream,
       fetchers = {};
 
@@ -934,9 +934,9 @@ ImapConnection.prototype._fetch = function(which, uids, options, what, cb) {
     what = options;
     options = {};
   }
-  prefix = (options.markSeen ? ' BODY.PEEK[' : ' BODY[');
   if (!Array.isArray(what))
     what = [what];
+
   for (var i = 0, wp, pprefix, len = what.length; i < len; ++i) {
     wp = what[i];
     if (wp.id !== undefined && !/^(?:[\d]+[\.]{0,1})*[\d]+$/.test(''+wp.id))
@@ -1117,8 +1117,12 @@ ImapConnection.prototype._fetch = function(which, uids, options, what, cb) {
     cmd += ' BODYSTRUCTURE';
   if (options.size)
     cmd += ' RFC822.SIZE';
-  if (toFetch)
+  if (toFetch) {
+    if (!options.markSeen)
+      cmd += toFetch.replace(/BODY\[/g, 'BODY.PEEK[');
+    else
       cmd += toFetch;
+  }
   cmd += ')';
 
   this._send(cmd, function(err) {