diff --git a/htdocs/admin/mails.php b/htdocs/admin/mails.php
index 8971f5a69d4..55316e47332 100644
--- a/htdocs/admin/mails.php
+++ b/htdocs/admin/mails.php
@@ -31,6 +31,7 @@ require_once DOL_DOCUMENT_ROOT.'/core/lib/files.lib.php';
 $langs->loadLangs(array("companies", "products", "admin", "mails", "other", "errors"));
 
 $action = GETPOST('action', 'aZ09');
+$cancel = GETPOST('cancel', 'aZ09');
 
 if (!$user->admin) accessforbidden();
 
@@ -64,33 +65,46 @@ complete_substitutions_array($substitutionarrayfortest, $langs);
  * Actions
  */
 
-if ($action == 'update' && empty($_POST["cancel"]))
+if ($action == 'update' && !$cancel)
 {
-	dolibarr_set_const($db, "MAIN_DISABLE_ALL_MAILS", GETPOST("MAIN_DISABLE_ALL_MAILS", 'int'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_FORCE_SENDTO", GETPOST("MAIN_MAIL_FORCE_SENDTO", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_ENABLED_USER_DEST_SELECT", GETPOST("MAIN_MAIL_ENABLED_USER_DEST_SELECT", 'int'), 'chaine', 0, '', $conf->entity);
-	// Send mode parameters
-	dolibarr_set_const($db, "MAIN_MAIL_SENDMODE", GETPOST("MAIN_MAIL_SENDMODE", 'aZ09'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_SMTP_PORT", GETPOST("MAIN_MAIL_SMTP_PORT", 'int'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_SMTP_SERVER", GETPOST("MAIN_MAIL_SMTP_SERVER", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_SMTPS_ID", GETPOST("MAIN_MAIL_SMTPS_ID", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_SMTPS_PW", GETPOST("MAIN_MAIL_SMTPS_PW", 'none'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_EMAIL_TLS", GETPOST("MAIN_MAIL_EMAIL_TLS", 'int'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_EMAIL_STARTTLS", GETPOST("MAIN_MAIL_EMAIL_STARTTLS", 'int'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_EMAIL_SMTP_ALLOW_SELF_SIGNED", GETPOST("MAIN_MAIL_EMAIL_SMTP_ALLOW_SELF_SIGNED", 'int'), 'chaine', 0, '', $conf->entity);
+	if (! $error && ! GETPOST("MAIN_MAIL_EMAIL_FROM", 'alphanohtml')) {
+		$error++;
+		setEventMessages($langs->trans("ErrorFieldRequired", $langs->transnoentitiesnoconv("MAIN_MAIL_EMAIL_FROM")), null, 'errors');
+		$action = 'edit';
+	}
+	if (! $error && ! isValidEmail(GETPOST("MAIN_MAIL_EMAIL_FROM", 'alphanohtml'))) {
+		$error++;
+		setEventMessages($langs->trans("ErrorBadEMail", GETPOST("MAIN_MAIL_EMAIL_FROM", 'alphanohtml')), null, 'errors');
+		$action = 'edit';
+	}
 
-	dolibarr_set_const($db, "MAIN_MAIL_EMAIL_DKIM_ENABLED", GETPOST("MAIN_MAIL_EMAIL_DKIM_ENABLED", 'int'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_EMAIL_DKIM_DOMAIN", GETPOST("MAIN_MAIL_EMAIL_DKIM_DOMAIN", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_EMAIL_DKIM_SELECTOR", GETPOST("MAIN_MAIL_EMAIL_DKIM_SELECTOR", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_EMAIL_DKIM_PRIVATE_KEY", GETPOST("MAIN_MAIL_EMAIL_DKIM_PRIVATE_KEY", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
-	// Content parameters
-	dolibarr_set_const($db, "MAIN_MAIL_EMAIL_FROM", GETPOST("MAIN_MAIL_EMAIL_FROM", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_ERRORS_TO", GETPOST("MAIN_MAIL_ERRORS_TO", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, "MAIN_MAIL_AUTOCOPY_TO", GETPOST("MAIN_MAIL_AUTOCOPY_TO", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
-	dolibarr_set_const($db, 'MAIN_MAIL_DEFAULT_FROMTYPE', GETPOST('MAIN_MAIL_DEFAULT_FROMTYPE', 'alphanohtml'), 'chaine', 0, '', $conf->entity);
+	if (! $error) {
+		dolibarr_set_const($db, "MAIN_DISABLE_ALL_MAILS", GETPOST("MAIN_DISABLE_ALL_MAILS", 'int'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_FORCE_SENDTO", GETPOST("MAIN_MAIL_FORCE_SENDTO", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_ENABLED_USER_DEST_SELECT", GETPOST("MAIN_MAIL_ENABLED_USER_DEST_SELECT", 'int'), 'chaine', 0, '', $conf->entity);
+		// Send mode parameters
+		dolibarr_set_const($db, "MAIN_MAIL_SENDMODE", GETPOST("MAIN_MAIL_SENDMODE", 'aZ09'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_SMTP_PORT", GETPOST("MAIN_MAIL_SMTP_PORT", 'int'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_SMTP_SERVER", GETPOST("MAIN_MAIL_SMTP_SERVER", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_SMTPS_ID", GETPOST("MAIN_MAIL_SMTPS_ID", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_SMTPS_PW", GETPOST("MAIN_MAIL_SMTPS_PW", 'none'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_EMAIL_TLS", GETPOST("MAIN_MAIL_EMAIL_TLS", 'int'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_EMAIL_STARTTLS", GETPOST("MAIN_MAIL_EMAIL_STARTTLS", 'int'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_EMAIL_SMTP_ALLOW_SELF_SIGNED", GETPOST("MAIN_MAIL_EMAIL_SMTP_ALLOW_SELF_SIGNED", 'int'), 'chaine', 0, '', $conf->entity);
 
-	header("Location: ".$_SERVER["PHP_SELF"]."?mainmenu=home&leftmenu=setup");
-	exit;
+		dolibarr_set_const($db, "MAIN_MAIL_EMAIL_DKIM_ENABLED", GETPOST("MAIN_MAIL_EMAIL_DKIM_ENABLED", 'int'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_EMAIL_DKIM_DOMAIN", GETPOST("MAIN_MAIL_EMAIL_DKIM_DOMAIN", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_EMAIL_DKIM_SELECTOR", GETPOST("MAIN_MAIL_EMAIL_DKIM_SELECTOR", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_EMAIL_DKIM_PRIVATE_KEY", GETPOST("MAIN_MAIL_EMAIL_DKIM_PRIVATE_KEY", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
+		// Content parameters
+		dolibarr_set_const($db, "MAIN_MAIL_EMAIL_FROM", GETPOST("MAIN_MAIL_EMAIL_FROM", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_ERRORS_TO", GETPOST("MAIN_MAIL_ERRORS_TO", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, "MAIN_MAIL_AUTOCOPY_TO", GETPOST("MAIN_MAIL_AUTOCOPY_TO", 'alphanohtml'), 'chaine', 0, '', $conf->entity);
+		dolibarr_set_const($db, 'MAIN_MAIL_DEFAULT_FROMTYPE', GETPOST('MAIN_MAIL_DEFAULT_FROMTYPE', 'alphanohtml'), 'chaine', 0, '', $conf->entity);
+
+		header("Location: ".$_SERVER["PHP_SELF"]."?mainmenu=home&leftmenu=setup");
+		exit;
+	}
 }
 
 
@@ -462,8 +476,8 @@ if ($action == 'edit')
 	print '<tr class="liste_titre"><td class="titlefieldmiddle">'.$langs->trans("OtherOptions").'</td><td></td></tr>';
 
 	// From
-	print '<tr class="oddeven"><td>'.$langs->trans("MAIN_MAIL_EMAIL_FROM", ini_get('sendmail_from') ?ini_get('sendmail_from') : $langs->transnoentities("Undefined")).'</td>';
-	print '<td><input class="flat" name="MAIN_MAIL_EMAIL_FROM" size="32" value="'.(!empty($conf->global->MAIN_MAIL_EMAIL_FROM) ? $conf->global->MAIN_MAIL_EMAIL_FROM : '');
+	print '<tr class="oddeven"><td class="fieldrequired">'.$langs->trans("MAIN_MAIL_EMAIL_FROM", ini_get('sendmail_from') ?ini_get('sendmail_from') : $langs->transnoentities("Undefined")).'</td>';
+	print '<td><input class="flat minwidth200" name="MAIN_MAIL_EMAIL_FROM" value="'.(!empty($conf->global->MAIN_MAIL_EMAIL_FROM) ? $conf->global->MAIN_MAIL_EMAIL_FROM : '');
 	print '"></td></tr>';
 
 	// Default from type
@@ -538,7 +552,7 @@ if ($action == 'edit')
 	print $text;
 
 	if ($conf->global->MAIN_MAIL_SENDMODE == 'mail' && empty($conf->global->MAIN_HIDE_WARNING_TO_ENCOURAGE_SMTP_SETUP)) {
-		print $form->textwithpicto('', $langs->trans("WarningPHPMail").'<br>'.$langs->trans("WarningPHPMailA").'<br>'.$langs->trans("WarningPHPMailB").'<br>'.$langs->trans("WarningPHPMailC"), 1, 'warning');
+		print $form->textwithpicto('', $langs->trans("WarningPHPMail").'<br>'.$langs->trans("WarningPHPMailA").'<br>'.$langs->trans("WarningPHPMailB").'<br>'.$langs->trans("WarningPHPMailC").'<br><br>'.$langs->trans("WarningPHPMailD"), 1, 'warning');
 	}
 
 	print '</td></tr>';
@@ -637,7 +651,7 @@ if ($action == 'edit')
 	print '</table>';
 
 	if ($conf->global->MAIN_MAIL_SENDMODE == 'mail' && empty($conf->global->MAIN_HIDE_WARNING_TO_ENCOURAGE_SMTP_SETUP)) {
-		print info_admin($langs->trans("WarningPHPMail").'<br>'.$langs->trans("WarningPHPMailA").'<br>'.$langs->trans("WarningPHPMailB").'<br>'.$langs->trans("WarningPHPMailC"), 0, 0, 'warning');
+		print info_admin($langs->trans("WarningPHPMail").'<br>'.$langs->trans("WarningPHPMailA").'<br>'.$langs->trans("WarningPHPMailB").'<br>'.$langs->trans("WarningPHPMailC").'<br><br>'.$langs->trans("WarningPHPMailD"), 0, 0, 'warning');
 	}
 
 	print '<br>';
diff --git a/htdocs/langs/en_US/admin.lang b/htdocs/langs/en_US/admin.lang
index 3091efcf7fd..e887b29879d 100644
--- a/htdocs/langs/en_US/admin.lang
+++ b/htdocs/langs/en_US/admin.lang
@@ -483,6 +483,7 @@ WarningPHPMail=WARNING: The setup to send emails from the application is using t
 WarningPHPMailA=- Using the server of the Email Service Provider increase the trustability of your email, so it increase the deliverablity without being flagging as SPAM
 WarningPHPMailB=- Some Email Service Providers (like Yahoo) do not allow you to send an email from another server than their own server. Your current setup uses the server of the application to send email and not the server of your email provider, so some recipients (the one compatible with the restrictive DMARC protocol), will ask your email provider if they can accept your email and some email providers (like Yahoo) may respond "no" because the server is not theirs, so few of your sent Emails may not be accepted for delivery (be careful also of your email provider's sending quota).
 WarningPHPMailC=- Using the SMTP server of your own Email Service Provider to send emails is also interesting so all emails sent from application will also be saved into your "Sent" directory of your mailbox.
+WarningPHPMailD=If the method 'PHP Mail' is really the method you would like to use, you can remove this warning by adding the constant MAIN_HIDE_WARNING_TO_ENCOURAGE_SMTP_SETUP to 1 in Home - Setup - Other.
 WarningPHPMail2=If your email SMTP provider need to restrict email client to some IP addresses (very rare), this is the IP address of the mail user agent (MUA) for your ERP CRM application: <strong>%s</strong>.
 WarningPHPMailSPF=If the domain name in your sender email address is protected by a SPF record (ask you domain name registar), you must add the following IPs in the SPF record of the DNS of your domain: <strong>%s</strong>.
 ClickToShowDescription=Click to show description