There have random 'no mx/a record' on some domain even try to change new dns server

In log file "dnsx: truncated packet" it might be that surgemail ignores response UDP query that has over 512 bytes limit.

Modern dns is not actually limited to 512 bytes payload for UDP anymore.

Here is some responses on linux dig command with some of public dns servers

yahoo.com.              631     IN      MX      1 mta7.am0.yahoodns.net.

------

$ dig yahoo.com mx @208.67.222.222

; <<>> DiG 9.10.3-P4-Debian <<>> yahoo.com mx @208.67.222.222
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 33504
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096 <----
;; QUESTION SECTION:
;yahoo.com.                     IN      MX

;; ANSWER SECTION:
yahoo.com.              334     IN      MX      1 mta5.am0.yahoodns.net.
yahoo.com.              334     IN      MX      1 mta6.am0.yahoodns.net.
yahoo.com.              334     IN      MX      1 mta7.am0.yahoodns.net.

;; Query time: 1 msec
;; SERVER: 208.67.222.222#53(208.67.222.222)
;; WHEN: Tue Oct 11 12:07:24 +07 2022
;; MSG SIZE  rcvd: 117

---------

; EDNS: version: 0, flags:; udp: 1232

; EDNS: version: 0, flags:; udp: 4096

It show that it return more than 512 bytes