Trouble-shooting general 530 SMTP errors (email receiving issues)

What SMTP error codes exist and how to deal with them. Debug error 530 when MX DNS domain records are missing.

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If you use a custom domain with MailSlurp and have periodic failures or 530 error messages from major providers like Yahoo and Gmail the MX records for your domain are likely misconfigured.

Investigating causes

Most email receiving issues that occur on MailSlurp are due to misconfigured domain name records.

A 530 failed to deliver error typically means you are using the private MX record. This record is not for public use and will fail. Please use only the 10 record for your domain and no other MX records.

First check the DNS records on your domain. Using a terminal and dig you can fetch the records like so:

> dig mx

; <<>> DiG 9.16.1-Ubuntu <<>> mx
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63450
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

; EDNS: version: 0, flags:; udp: 65494
;			IN	MX


;; Query time: 35 msec
;; WHEN: Mi Jan 06 18:30:15 CET 2021
;; MSG SIZE  rcvd: 94

You should have one MX record only with the value:

ttl: 600 
type: MX (IN)
record: 10`

Note period at the end of the name and record is required (if your DNS settings allow it) and is valid for DNS server names and records.

Additional causes

If you create inboxes that use a subdomain your account must be manually configured. Please contact support in this case.