node-red-node-email does not fallback to IPv4 if IPv6 connection fails

[stgnet]

Which node are you reporting and issue on?

node-red-node-email

What are the steps to reproduce?

Configure an outgoing email using smtp.gmail.com, but running on a IPv4 only network (for example, wifi router or computer without IPv6 enabled). Because smtp.gmail.com answers with a AAAA record first, and that's the one used, the connection will fail.

What happens?

Error: connect EHOSTUNREACH 2607:f8b0:4002:c0f::6d:465 - Local (:::49175)
at internalConnect (node:net:1110:16)
at defaultTriggerAsyncIdScope (node:internal/async_hooks:472:18)
at node:net:1356:9
at process.processTicksAndRejections (node:internal/process/task_queues:84:11)

What did you expect to happen?

After IPv6 connection fails, try the next DNS record which would be an IPv4 address, and then it would succeed. I know this is possible because I was able to patch nodemailer to skip AAAA records. It may however be not as simple to add an actual retry mechanism to the logic.

Environment

• Node-RED version:4.1.2
• Node.js version: 25.2.1
• npm version: n/a
• Platform/OS: mac/macos/brew
• Browser: firefox

[dceejay]

As you have noted we rely on the nodemailer package for the actual connection so I'm not sure what we can do about this - Looking at a similar issue on the nodemailer repo I can see this response from the author - nodemailer/nodemailer#1743 (comment) - To me this indicates that a) it should try ipv4 first and b) maybe there is something amiss with the low level resolution - can you try a different DNS server ? (eg 1.1.1.1)
It could also be down to the way nodejs itself handles ipv6 - I note you are using nodejs25 - we only support LTS versions - so 22 or 24. Can you see if they give the same result ?

[stgnet]

Yeah, I understand it's probably an issue that should be solved at the underlying nodemailer repo instead.

Trying IPv6 first is I think preferred for the long term good of the internet, but the fact that IPv4 is not tried as a fallback, or even worse that all available DNS records are not tried (in any order) until success is really the fatal flaw here.

I tried using the node --dns-result-order=ipv4first but that doesn't affect the operation of nodemailer's use of DNS records.

[dceejay]

Did you try another DNS server for your connection ? It may reply in a different order ?

[stgnet]

I attempted to find any number of solutions including different dns servers, but unfortunately the order is nearly always AAAA first, and in that case it 100% fails on my IPv4 only network. I've started a separate bug report on nodemailer in the meantime.

[dceejay]

ok - thanks, if I set up ipv4 only on my Pi here it still works fine for me using 1.1.1.1 - and nodev20, so I can't recreate locally. But yes - lots of other potential differences in networks from Pi to gmail - so - I don't think there is anything for us to fix here.