- if (!smtp_get_interface(rs, host_af, addrlist, &interface, tid))
- return FALSE;
- pistring = string_sprintf("%s/%s", pistring, interface);
+ uschar * s = ob->interface;
+ if (s && *s)
+ {
+ if (!smtp_get_interface(s, host_af, addrlist, &interface, tid))
+ return FALSE;
+ pistring = string_sprintf("%s/%s", pistring, interface);
+ }