- snprintf(mid, sizeof(mid), "MESSAGE_ID=" SD_ID128_FORMAT_STR, SD_ID128_FORMAT_VAL(message_id));
- char_array_0(mid);
- IOVEC_SET_STRING(iovec[n++], mid);
+ if (!sd_id128_equal(message_id, SD_ID128_NULL)) {
+ snprintf(mid, sizeof(mid), "MESSAGE_ID=" SD_ID128_FORMAT_STR, SD_ID128_FORMAT_VAL(message_id));
+ char_array_0(mid);
+ IOVEC_SET_STRING(iovec[n++], mid);
+ }