diff --git a/ext/mbstring/mbstring.c b/ext/mbstring/mbstring.c
index c5331ef017af..805c4084352d 100644
--- a/ext/mbstring/mbstring.c
+++ b/ext/mbstring/mbstring.c
@@ -4633,9 +4633,8 @@ PHP_FUNCTION(mb_send_mail)
 
 	unsigned int num_errors = 0;
 	zend_string *tmpstr = mb_fast_convert((unsigned char*)message, message_len, msg_enc, tran_cs, '?', MBFL_OUTPUTFILTER_ILLEGAL_MODE_CHAR, &num_errors);
-	zend_string *conv = mb_fast_convert((unsigned char*)ZSTR_VAL(tmpstr), ZSTR_LEN(tmpstr), &mbfl_encoding_8bit, body_enc, '?', MBFL_OUTPUTFILTER_ILLEGAL_MODE_CHAR, &num_errors);
+	zend_string *converted_message = mb_fast_convert((unsigned char*)ZSTR_VAL(tmpstr), ZSTR_LEN(tmpstr), &mbfl_encoding_8bit, body_enc, '?', MBFL_OUTPUTFILTER_ILLEGAL_MODE_CHAR, &num_errors);
 	zend_string_free(tmpstr);
-	message = ZSTR_VAL(conv);
 
 	/* other headers */
 #define PHP_MBSTR_MAIL_MIME_HEADER1 "MIME-Version: 1.0"
@@ -4703,7 +4702,7 @@ PHP_FUNCTION(mb_send_mail)
 		extra_cmd = php_escape_shell_cmd(extra_cmd);
 	}
 
-	RETVAL_BOOL(php_mail(to_r, ZSTR_VAL(subject), message, ZSTR_VAL(str_headers), extra_cmd));
+	RETVAL_BOOL(php_mail(to_r, ZSTR_VAL(subject), converted_message, str_headers, extra_cmd));
 
 	if (extra_cmd) {
 		zend_string_release_ex(extra_cmd, 0);
@@ -4712,7 +4711,7 @@ PHP_FUNCTION(mb_send_mail)
 		efree(to_r);
 	}
 	zend_string_release(subject);
-	zend_string_free(conv);
+	zend_string_free(converted_message);
 	zend_hash_destroy(&ht_headers);
 	if (str_headers) {
 		zend_string_release_ex(str_headers, 0);
diff --git a/ext/standard/basic_functions.c b/ext/standard/basic_functions.c
index c108900103cc..4d9e1dc82bc7 100644
--- a/ext/standard/basic_functions.c
+++ b/ext/standard/basic_functions.c
@@ -1353,7 +1353,7 @@ PHPAPI zend_result _php_error_log(int opt_err, const zend_string *message, const
 	switch (opt_err)
 	{
 		case 1:		/*send an email */
-			if (!php_mail(ZSTR_VAL(opt), "PHP error_log message", ZSTR_VAL(message), ZSTR_VAL(headers), NULL)) {
+			if (!php_mail(ZSTR_VAL(opt), "PHP error_log message", message, headers, NULL)) {
 				return FAILURE;
 			}
 			break;
diff --git a/ext/standard/mail.c b/ext/standard/mail.c
index 395c7bb81d4f..c185afa2937a 100644
--- a/ext/standard/mail.c
+++ b/ext/standard/mail.c
@@ -21,7 +21,6 @@
 #include "php.h"
 #include "ext/standard/info.h"
 #include "ext/standard/php_string.h"
-#include "ext/standard/basic_functions.h"
 #include "ext/date/php_date.h"
 #include "zend_smart_str.h"
 
@@ -154,10 +153,6 @@ static void php_mail_build_headers_elem(smart_str *s, const zend_string *key, zv
 				case CONTAINS_NULL:
 					zend_value_error("Header \"%s\" contains NULL character that is not allowed in the header", ZSTR_VAL(key));
 					return;
-				default:
-					// fallback
-					zend_value_error("Header \"%s\" has invalid format, or contains invalid characters", ZSTR_VAL(key));
-					return;
 			}
 			smart_str_append(s, key);
 			smart_str_appendl(s, ": ", 2);
@@ -265,19 +260,20 @@ PHPAPI zend_string *php_mail_build_headers(const HashTable *headers)
 /* {{{ Send an email message */
 PHP_FUNCTION(mail)
 {
-	char *to=NULL, *message=NULL;
+	char *to=NULL;
 	char *subject=NULL;
+	zend_string *message;
 	zend_string *extra_cmd=NULL;
 	zend_string *headers_str = NULL;
 	HashTable *headers_ht = NULL;
-	size_t to_len, message_len;
+	size_t to_len;
 	size_t subject_len, i;
 	char *to_r, *subject_r;
 
 	ZEND_PARSE_PARAMETERS_START(3, 5)
 		Z_PARAM_PATH(to, to_len)
 		Z_PARAM_PATH(subject, subject_len)
-		Z_PARAM_PATH(message, message_len)
+		Z_PARAM_PATH_STR(message)
 		Z_PARAM_OPTIONAL
 		Z_PARAM_ARRAY_HT_OR_STR(headers_ht, headers_str)
 		Z_PARAM_PATH_STR(extra_cmd)
@@ -343,7 +339,7 @@ PHP_FUNCTION(mail)
 		extra_cmd = php_escape_shell_cmd(extra_cmd);
 	}
 
-	if (php_mail(to_r, subject_r, message, headers_str && ZSTR_LEN(headers_str) ? ZSTR_VAL(headers_str) : NULL, extra_cmd)) {
+	if (php_mail(to_r, subject_r, message, headers_str, extra_cmd)) {
 		RETVAL_TRUE;
 	} else {
 		RETVAL_FALSE;
@@ -396,31 +392,33 @@ static void php_mail_log_to_file(const zend_string *filename, const char *messag
 }
 
 
-static int php_mail_detect_multiple_crlf(const char *hdr) {
+static bool php_mail_detect_multiple_crlf(const zend_string *headers) {
 	/* This function detects multiple/malformed multiple newlines. */
 
-	if (!hdr || !strlen(hdr)) {
-		return 0;
+	if (!headers || !ZSTR_LEN(headers)) {
+		return false;
 	}
 
+	const char *end = ZSTR_VAL(headers) + ZSTR_LEN(headers);
+	const char *hdr = ZSTR_VAL(headers);
 	/* Should not have any newlines at the beginning. */
 	/* RFC 2822 2.2. Header Fields */
 	if (*hdr < 33 || *hdr > 126 || *hdr == ':') {
-		return 1;
+		return true;
 	}
 
-	while(*hdr) {
+	while (hdr < end) {
 		if (*hdr == '\r') {
 			if (*(hdr+1) == '\0' || *(hdr+1) == '\r' || (*(hdr+1) == '\n' && (*(hdr+2) == '\0' || *(hdr+2) == '\n' || *(hdr+2) == '\r'))) {
 				/* Malformed or multiple newlines. */
-				return 1;
+				return true;
 			} else {
 				hdr += 2;
 			}
 		} else if (*hdr == '\n') {
 			if (*(hdr+1) == '\0' || *(hdr+1) == '\r' || *(hdr+1) == '\n') {
 				/* Malformed or multiple newlines. */
-				return 1;
+				return true;
 			} else {
 				hdr += 2;
 			}
@@ -429,35 +427,35 @@ static int php_mail_detect_multiple_crlf(const char *hdr) {
 		}
 	}
 
-	return 0;
+	return false;
 }
 
 
 /* {{{ php_mail */
-PHPAPI bool php_mail(const char *to, const char *subject, const char *message, const char *headers, const zend_string *extra_cmd)
+PHPAPI bool php_mail(const char *to, const char *subject, const zend_string *message, const zend_string *headers, const zend_string *extra_cmd)
 {
 	FILE *sendmail;
 	char *sendmail_path = INI_STR("sendmail_path");
 	char *sendmail_cmd = NULL;
 	const zend_string *mail_log = zend_ini_str(ZEND_STRL("mail.log"), false);
-	const char *hdr = headers;
-	char *ahdr = NULL;
 #if PHP_SIGCHILD
 	void (*sig_handler)(int) = NULL;
 #endif
 
 #define MAIL_RET(val) \
-	if (ahdr != NULL) {	\
-		efree(ahdr);	\
-	}	\
-	return val;	\
+	if (headers_with_x_php_header != NULL) { \
+		zend_string_release_ex(headers_with_x_php_header, false); \
+	} \
+	return val; \
 
 	if (mail_log && ZSTR_LEN(mail_log)) {
 		char *logline;
+		const char *hdr = headers ? ZSTR_VAL(headers) : "";
 
-		spprintf(&logline, 0, "mail() on [%s:%d]: To: %s -- Headers: %s -- Subject: %s", zend_get_executed_filename(), zend_get_executed_lineno(), to, hdr ? hdr : "", subject);
+		spprintf(&logline, 0, "mail() on [%s:%d]: To: %s -- Headers: %s -- Subject: %s",
+			zend_get_executed_filename(), zend_get_executed_lineno(), to, hdr, subject);
 
-		if (hdr) {
+		if (headers && ZSTR_LEN(headers)) {
 			php_mail_log_crlf_to_spaces(logline);
 		}
 
@@ -485,7 +483,7 @@ PHPAPI bool php_mail(const char *to, const char *subject, const char *message, c
 	}
 
 	if (EG(exception)) {
-		MAIL_RET(false);
+		return false;
 	}
 
 	const char *line_sep;
@@ -510,22 +508,25 @@ PHPAPI bool php_mail(const char *to, const char *subject, const char *message, c
 		line_sep = PG(mail_mixed_lf_and_crlf) ? "\n" : "\r\n";
 	}
 
+	zend_string *headers_with_x_php_header = NULL;
 	if (PG(mail_x_header)) {
 		const char *tmp = zend_get_executed_filename();
 		zend_string *f;
 
 		f = php_basename(tmp, strlen(tmp), NULL, 0);
 
-		if (headers != NULL && *headers) {
-			spprintf(&ahdr, 0, "X-PHP-Originating-Script: " ZEND_LONG_FMT ":%s%s%s", php_getuid(), ZSTR_VAL(f), line_sep, headers);
+		if (headers != NULL && ZSTR_LEN(headers)) {
+			headers_with_x_php_header = strpprintf(0, "X-PHP-Originating-Script: " ZEND_LONG_FMT ":%s%s%s",
+				php_getuid(), ZSTR_VAL(f), line_sep, ZSTR_VAL(headers));
 		} else {
-			spprintf(&ahdr, 0, "X-PHP-Originating-Script: " ZEND_LONG_FMT ":%s", php_getuid(), ZSTR_VAL(f));
+			headers_with_x_php_header = strpprintf(0, "X-PHP-Originating-Script: " ZEND_LONG_FMT ":%s",
+				php_getuid(), ZSTR_VAL(f));
 		}
-		hdr = ahdr;
 		zend_string_release_ex(f, 0);
+		headers = headers_with_x_php_header;
 	}
 
-	if (hdr && php_mail_detect_multiple_crlf(hdr)) {
+	if (php_mail_detect_multiple_crlf(headers)) {
 		php_error_docref(NULL, E_WARNING, "Multiple or malformed newlines found in additional_header");
 		MAIL_RET(false);
 	}
@@ -536,7 +537,8 @@ PHPAPI bool php_mail(const char *to, const char *subject, const char *message, c
 		char *tsm_errmsg = NULL;
 
 		/* handle old style win smtp sending */
-		if (TSendMail(INI_STR("SMTP"), &tsm_err, &tsm_errmsg, hdr, subject, to, message) == FAILURE) {
+		int status = TSendMail(INI_STR("SMTP"), &tsm_err, &tsm_errmsg, headers ? ZSTR_VAL(headers) : NULL, subject, to, ZSTR_VAL(message));
+		if (status == FAILURE) {
 			if (tsm_errmsg) {
 				php_error_docref(NULL, E_WARNING, "%s", tsm_errmsg);
 				efree(tsm_errmsg);
@@ -579,122 +581,121 @@ PHPAPI bool php_mail(const char *to, const char *subject, const char *message, c
 		efree (sendmail_cmd);
 	}
 
-	if (sendmail) {
-		int ret;
-#ifndef PHP_WIN32
-		if (EACCES == errno) {
-			php_error_docref(NULL, E_WARNING, "Permission denied: unable to execute shell to run mail delivery binary '%s'", sendmail_path);
-			pclose(sendmail);
+	if (UNEXPECTED(!sendmail)) {
+		php_error_docref(NULL, E_WARNING, "Could not execute mail delivery program '%s'", sendmail_path);
 #if PHP_SIGCHILD
-			/* Restore handler in case of error on Windows
-			   Not sure if this applicable on Win but just in case. */
-			if (sig_handler) {
-				signal(SIGCHLD, sig_handler);
-			}
-#endif
-			MAIL_RET(false);
+		if (sig_handler) {
+			signal(SIGCHLD, sig_handler);
 		}
 #endif
-		fprintf(sendmail, "To: %s%s", to, line_sep);
-		fprintf(sendmail, "Subject: %s%s", subject, line_sep);
-		if (hdr != NULL) {
-			fprintf(sendmail, "%s%s", hdr, line_sep);
+		MAIL_RET(false);
+	}
+
+#ifndef PHP_WIN32
+	if (EACCES == errno) {
+		php_error_docref(NULL, E_WARNING, "Permission denied: unable to execute shell to run mail delivery binary '%s'", sendmail_path);
+		pclose(sendmail);
+#if PHP_SIGCHILD
+		/* Restore handler in case of error on Windows
+		   Not sure if this applicable on Win but just in case. */
+		if (sig_handler) {
+			signal(SIGCHLD, sig_handler);
 		}
+#endif
+		MAIL_RET(false);
+	}
+#endif
+	fprintf(sendmail, "To: %s%s", to, line_sep);
+	fprintf(sendmail, "Subject: %s%s", subject, line_sep);
+	if (headers && ZSTR_LEN(headers)) {
+		fprintf(sendmail, "%s%s", ZSTR_VAL(headers), line_sep);
+	}
 
-		fprintf(sendmail, "%s", line_sep);
-		
-		if (cr_lf_mode && zend_string_equals_literal(cr_lf_mode, "lf")) {
-			char *converted_message = NULL;
-			size_t msg_len = strlen(message);
-			size_t new_len = 0;
-
-			if (msg_len > 0) {
-				for (size_t i = 0; i < msg_len - 1; ++i) {
-					if (message[i] == '\r' && message[i + 1] == '\n') {
-						++new_len;
-					}
+	fprintf(sendmail, "%s", line_sep);
+
+	if (cr_lf_mode && zend_string_equals_literal(cr_lf_mode, "lf")) {
+		char *converted_message = NULL;
+		size_t msg_len = ZSTR_LEN(message);
+		size_t new_len = 0;
+
+		if (msg_len > 0) {
+			for (size_t i = 0; i < msg_len - 1; ++i) {
+				if (ZSTR_VAL(message)[i] == '\r' && ZSTR_VAL(message)[i + 1] == '\n') {
+					++new_len;
 				}
+			}
 
-				if (new_len == 0) {
-					fprintf(sendmail, "%s", message);
-				} else {
-					converted_message = emalloc(msg_len - new_len + 1);
-					size_t j = 0;
-					for (size_t i = 0; i < msg_len; ++i) {
-						if (i < msg_len - 1 && message[i] == '\r' && message[i + 1] == '\n') {
-							converted_message[j++] = '\n';
-							++i; /* skip LF part */
-						} else {
-							converted_message[j++] = message[i];
-						}
+			if (new_len == 0) {
+				fprintf(sendmail, "%s", ZSTR_VAL(message));
+			} else {
+				converted_message = emalloc(msg_len - new_len + 1);
+				size_t j = 0;
+				for (size_t i = 0; i < msg_len; ++i) {
+					if (i < msg_len - 1 && ZSTR_VAL(message)[i] == '\r' && ZSTR_VAL(message)[i + 1] == '\n') {
+						converted_message[j++] = '\n';
+						++i; /* skip LF part */
+					} else {
+						converted_message[j++] = ZSTR_VAL(message)[i];
 					}
-
-					converted_message[j] = '\0';
-					fprintf(sendmail, "%s", converted_message);
-					efree(converted_message);
 				}
+
+				converted_message[j] = '\0';
+				fprintf(sendmail, "%s", converted_message);
+				efree(converted_message);
 			}
-		} else {
-			fprintf(sendmail, "%s", message);
 		}
+	} else {
+		fprintf(sendmail, "%s", ZSTR_VAL(message));
+	}
 
-		fprintf(sendmail, "%s", line_sep);
+	fprintf(sendmail, "%s", line_sep);
+
+	int ret;
 #ifdef PHP_WIN32
-		ret = pclose(sendmail);
+	ret = pclose(sendmail);
 
 #if PHP_SIGCHILD
-		if (sig_handler) {
-			signal(SIGCHLD, sig_handler);
-		}
+	if (sig_handler) {
+		signal(SIGCHLD, sig_handler);
+	}
 #endif
 #else
-		int wstatus = pclose(sendmail);
+	int wstatus = pclose(sendmail);
 #if PHP_SIGCHILD
-		if (sig_handler) {
-			signal(SIGCHLD, sig_handler);
-		}
+	if (sig_handler) {
+		signal(SIGCHLD, sig_handler);
+	}
 #endif
-		/* Determine the wait(2) exit status */
-		if (wstatus == -1) {
-			php_error_docref(NULL, E_WARNING, "Sendmail pclose failed %d (%s)", errno, strerror(errno));
-			MAIL_RET(false);
-		} else if (WIFSIGNALED(wstatus)) {
-			php_error_docref(NULL, E_WARNING, "Sendmail killed by signal %d (%s)", WTERMSIG(wstatus), strsignal(WTERMSIG(wstatus)));
-			MAIL_RET(false);
+	/* Determine the wait(2) exit status */
+	if (wstatus == -1) {
+		php_error_docref(NULL, E_WARNING, "Sendmail pclose failed %d (%s)", errno, strerror(errno));
+		MAIL_RET(false);
+	} else if (WIFSIGNALED(wstatus)) {
+		php_error_docref(NULL, E_WARNING, "Sendmail killed by signal %d (%s)", WTERMSIG(wstatus), strsignal(WTERMSIG(wstatus)));
+		MAIL_RET(false);
+	} else {
+		if (WIFEXITED(wstatus)) {
+			ret = WEXITSTATUS(wstatus);
 		} else {
-			if (WIFEXITED(wstatus)) {
-				ret = WEXITSTATUS(wstatus);
-			} else {
-				php_error_docref(NULL, E_WARNING, "Sendmail did not exit");
-				MAIL_RET(false);
-			}
+			php_error_docref(NULL, E_WARNING, "Sendmail did not exit");
+			MAIL_RET(false);
 		}
+	}
 #endif
 
 #if defined(EX_TEMPFAIL)
-		if ((ret != EX_OK)&&(ret != EX_TEMPFAIL))
+	if ((ret != EX_OK)&&(ret != EX_TEMPFAIL))
 #elif defined(EX_OK)
-		if (ret != EX_OK)
+	if (ret != EX_OK)
 #else
-		if (ret != 0)
-#endif
-		{
-			php_error_docref(NULL, E_WARNING, "Sendmail exited with non-zero exit code %d", ret);
-			MAIL_RET(false);
-		} else {
-			MAIL_RET(true);
-		}
-	} else {
-		php_error_docref(NULL, E_WARNING, "Could not execute mail delivery program '%s'", sendmail_path);
-#if PHP_SIGCHILD
-		if (sig_handler) {
-			signal(SIGCHLD, sig_handler);
-		}
+	if (ret != 0)
 #endif
+	{
+		php_error_docref(NULL, E_WARNING, "Sendmail exited with non-zero exit code %d", ret);
 		MAIL_RET(false);
+	} else {
+		MAIL_RET(true);
 	}
-
-	MAIL_RET(true); /* never reached */
 }
 /* }}} */
 
diff --git a/ext/standard/php_mail.h b/ext/standard/php_mail.h
index bebb526699d0..ade6a4124401 100644
--- a/ext/standard/php_mail.h
+++ b/ext/standard/php_mail.h
@@ -20,6 +20,6 @@
 PHP_MINFO_FUNCTION(mail);
 
 PHPAPI zend_string *php_mail_build_headers(const HashTable *headers);
-PHPAPI extern bool php_mail(const char *to, const char *subject, const char *message, const char *headers, const zend_string *extra_cmd);
+PHPAPI extern bool php_mail(const char *to, const char *subject, const zend_string *message, const zend_string *headers, const zend_string *extra_cmd);
 
 #endif /* PHP_MAIL_H */