diff --git a/htdocs/core/class/CMailFile.class.php b/htdocs/core/class/CMailFile.class.php
index 0f80563e293..f1579d5b4e2 100644
--- a/htdocs/core/class/CMailFile.class.php
+++ b/htdocs/core/class/CMailFile.class.php
@@ -962,7 +962,21 @@ class CMailFile
 						$this->html_images[$i]["name"] = $img;
 
 						// Content type
-						$ext = preg_replace('/^.*\.(\w{3,4})$/e', 'strtolower("$1")', $img);
+						/*
+						 * preg_replace /e modifier is deprecated in PHP 5.5
+						 * but anonymous functions for use in preg_replace_callback are only available from 5.3.0
+						 */
+						if (version_compare(PHP_VERSION, '5.3.0') >= 0) {
+							$ext = preg_replace_callback(
+								'/^.*\.(\w{3,4})$/',
+								function ($m) {
+									return strtolower($m[1]);
+								},
+								$img
+							);
+						} else {
+							$ext = preg_replace('/^.*\.(\w{3,4})$/e', 'strtolower("$1")', $img);
+						}
 						$this->html_images[$i]["content_type"] = $this->image_types[$ext];
 
 						// cid
@@ -1076,4 +1090,4 @@ class CMailFile
 	}
 }
 
-?>
\ No newline at end of file
+?>
diff --git a/htdocs/core/lib/xcal.lib.php b/htdocs/core/lib/xcal.lib.php
index 298f1728b7c..6559e8043c0 100644
--- a/htdocs/core/lib/xcal.lib.php
+++ b/htdocs/core/lib/xcal.lib.php
@@ -515,9 +515,23 @@ function quotedPrintEncode($str,$forcal=0)
 function quotedPrintDecode($str)
 {
 	$out = preg_replace('/=\r?\n/', '', $str);
-	$out = preg_replace('/=([A-F0-9]{2})/e', chr(hexdec('\\1')), $out);
+	/*
+	 * preg_replace /e modifier is deprecated in PHP 5.5
+	 * but anonymous functions for use in preg_replace_callback are only available from 5.3.0
+	 */
+	if (version_compare(PHP_VERSION, '5.3.0') >= 0) {
+		$out = preg_replace_callback(
+			'/=([A-F0-9]{2})/',
+			function ($m) {
+				return chr(hexdec($m[1]));
+			},
+			$out
+		);
+	} else {
+		$out = preg_replace('/=([A-F0-9]{2})/e', chr(hexdec('\\1')), $out);
+	}
 
 	return trim($out);
 }
 
-?>
\ No newline at end of file
+?>
diff --git a/htdocs/includes/nusoap/lib/Mail/mime.php b/htdocs/includes/nusoap/lib/Mail/mime.php
index 55b32be55b1..3d44f050062 100644
--- a/htdocs/includes/nusoap/lib/Mail/mime.php
+++ b/htdocs/includes/nusoap/lib/Mail/mime.php
@@ -677,10 +677,24 @@ class Mail_mime
         foreach ($input as $hdr_name => $hdr_value) {
             preg_match_all('/(\w*[\x80-\xFF]+\w*)/', $hdr_value, $matches);
             foreach ($matches[1] as $value) {
-                $replacement = preg_replace('/([\x80-\xFF])/e',
-                                            '"=" .
-                                            strtoupper(dechex(ord("\1")))',
-                                            $value);
+                /*
+                 * preg_replace /e modifier is deprecated in PHP 5.5
+                 * but anonymous functions for use in preg_replace_callback are only available from 5.3.0
+                 */
+                if (version_compare(PHP_VERSION, '5.3.0') >= 0) {
+                    $replacement = preg_replace_callback(
+                        '/([\x80-\xFF])/',
+                        function ($m) {
+                            return "=" . strtoupper(dechex(ord($m[1])));
+                        },
+                        $value
+                    );
+                } else {
+                    $replacement = preg_replace('/([\x80-\xFF])/e',
+                                                '"=" .
+                                                strtoupper(dechex(ord("\1")))',
+                                                $value);
+                }
                 $hdr_value = str_replace($value, '=?' .
                                          $this->_build_params['head_charset'] .
                                          '?Q?' . $replacement . '?=',