In the code example that follows, the value of an option named mail_url is retrieved. Before calling mtaOptionString(), a default value is set for the variable to receive the value of the option. If the option was not specified, then the variable will retain that default setting. If the option was specified, then the variable will assume the value set by that specification.
char url; strcpy(url, "mail_to:email@example.com"); mtaOptionString(opt, "mail_url", 0, url, NULL, sizeof(url));