Mail Bounce due to Invalid string MX record

I'm new to managing a mail server and I encounter an issue with sending a message to a certain domain.

Our emails are bouncing back on us with the error of the Invalid MX record string.

I'm using Lotus Domino.

Below the message I got on bounce email:

[<00>] XMail bounce: Rcpt=[[email protected]];Error=[Invalid MX records string format]

[<01>] Error sending message [1620000931566.5a6ffb70.1089.1bb0f.protect] from [protect.cardmri.com].

ID: <21050300-6320-0000-0000-000002A2C8E0> Mail From: [email protected] Rcpt To: [email protected] Server: [smart.com.ph]

[<02>] The reason of the delivery failure was: Invalid MX records string format

Solution 1:

The destination domain has a malformed MX record.

$ dig mx smart.com.ph

; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.amzn2.4 <<>> mx smart.com.ph
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4883
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;smart.com.ph.                  IN      MX

;; ANSWER SECTION:
smart.com.ph.           796     IN      MX      20 mx2.hc370-38.ap.iphmx.com\032.
smart.com.ph.           796     IN      MX      10 mx1.hc370-38.ap.iphmx.com.

That \032 should not be there.

There's nothing you, as a sender, can do to fix this; the recipient needs to correct their DNS record.