mbbsd: Send email notification to user when contact email is changed

An email notification will be sent to the user's old email address on file.
This is not sent if there is no email on file.

mbbsd/register.c

@@ -1687,6 +1687,18 @@ u_register()
 
 #ifdef USEREC_EMAIL_IS_CONTACT
 
+static int notify_email_change(const char *userid, const char *email)
+{
+    char subject[128];
+    int ret;
+
+    snprintf(subject, sizeof(subject), " %s - %s (%s) - 聯絡信箱已更變",
+	     BBSNAME, userid, fromhost);
+
+    ret = bsmtp("etc/emailchanged", subject, email, "non-exist");
+
+    return ret > 0 ? 0 : -1;
+}
 void
 change_contact_email()
 {
@@ -1705,6 +1717,10 @@ change_contact_email()
     log_filef(logfn, LOG_CREAT, "%s %s (ContactEmail) %s -> %s\n",
 	      Cdatelite(&now), fromhost, cuser.email, email);
 
+    // Send notification to old email address if it was valid
+    if (is_valid_addr(cuser.email))
+	notify_email_change(cuser.userid, cuser.email);
+
     // Write.
     pwcuSetEmail(email);
 

sample/etc/Makefile

@@ -8,6 +8,7 @@ FILES=	Welcome		Welcome_login	\
 	feast		sysop		banip.conf	\
 	ve.hlp		board.help	boardlist.help	\
 	editable	expire2.conf	domain_name_query.cidr	\
+	passwdchanged	emailchanged	\
 	banemail	whitemail	whitemail.notice ziphome.exclude
 
 all:

sample/etc/emailchanged

@@ -0,0 +1,23 @@
+Message below is written in Chinese/Big5.
+If you cannot read Chinese/Big5, skip to English section.
+-------------------------------------------------------------
+�˷R���ϥΪ̱z�n:
+
+	�z���p���H�c�w�g����.
+
+	�p�����z���H�ާ@, �Щ������ʫH.
+
+	�p�D�z���H�ާ@, �Хߨ�n�J�íק�z���K�X���p���H�c.
+
+-------------------------------------------------------------
+Dear user,
+
+	This mail is to confirm your contact email address
+	has been changed.
+
+	If it was you, you may discard this email.
+
+	If it was not you, please login immediately and
+	change your password and contact email.
+
+-------------------------------------------------------------