delv is the successor to dig, and both are tools that come as part of BIND the DNS server for making queries and debugging DNS. Delv happens to understand DNSSEC a bit better, so if you ever need to debug that, it is handy to have.
In this case dig or delv would be fine. You can also use https://mxtoolbox.com/SuperTool.aspx and pick "MX lookup" to find the MX records. It will also resolve the IPs, both IPv4 and IPv6 (A and AAAA) for you for the returned records.
Their supertool also breaks down SPF records, for example, into their meaning and tells you if they're valid or not. I think other links were posted that do similar things but I haven't had a chance to try them yet.
I've mentioned reverse pointers in various cases, delv can do those lookups too. Here is how you do it: first you find the IP of say mail-ed1-x529.google.com, which happens to be a mailserver of Google that was the last step before my mail server when sending myself a message from gmail. For a bit of a change, this is an IPv6 only server, and it has IP 2a00:1450:4864:20::529. So let's look it up with -x:
There are some special domains of the format <reverse-ip-address>.in-addr.arpa and <reverse-ipv6-address-digits>.ip6.arpa that point (PTR) to the DNS name. dig/delv know how to reverse and query appropriately. You can use this for precisely this reason: to look up the intended host. This makes for a nice sanity check during email sending, because in SMTP I can announce myself as any host I like, but the recipient can do a reverse lookup on my IP and see if I'm telling the truth.
One of, but my no means the only, reasons you can't send email from a home connection is because you announce yourself as smtp.zahllos.example but your reverse dns resolves to something like <somegeneratedhostname>.dynamic.residential.isp.com. You can find out yours: type "what is my ip" into google, copy-paste that and do a delv -x on it and see what your "hostname" is according to the internet.
In this case dig or delv would be fine. You can also use https://mxtoolbox.com/SuperTool.aspx and pick "MX lookup" to find the MX records. It will also resolve the IPs, both IPv4 and IPv6 (A and AAAA) for you for the returned records.
Their supertool also breaks down SPF records, for example, into their meaning and tells you if they're valid or not. I think other links were posted that do similar things but I haven't had a chance to try them yet.
I've mentioned reverse pointers in various cases, delv can do those lookups too. Here is how you do it: first you find the IP of say mail-ed1-x529.google.com, which happens to be a mailserver of Google that was the last step before my mail server when sending myself a message from gmail. For a bit of a change, this is an IPv6 only server, and it has IP 2a00:1450:4864:20::529. So let's look it up with -x:
There are some special domains of the format <reverse-ip-address>.in-addr.arpa and <reverse-ipv6-address-digits>.ip6.arpa that point (PTR) to the DNS name. dig/delv know how to reverse and query appropriately. You can use this for precisely this reason: to look up the intended host. This makes for a nice sanity check during email sending, because in SMTP I can announce myself as any host I like, but the recipient can do a reverse lookup on my IP and see if I'm telling the truth.One of, but my no means the only, reasons you can't send email from a home connection is because you announce yourself as smtp.zahllos.example but your reverse dns resolves to something like <somegeneratedhostname>.dynamic.residential.isp.com. You can find out yours: type "what is my ip" into google, copy-paste that and do a delv -x on it and see what your "hostname" is according to the internet.