Reply to Mail app fails the internet.nl mail test on cipher suites on Sat, 08 Aug 2026 09:53:11 GMT

imc67 — Sat, 08 Aug 2026 09:53:11 GMT

The opportunistic-TLS point is fair and I'll concede it — on port 25 a weak cipher beats a plaintext fallback, and internet.nl's model implicitly assumes an enforcing world (DANE, MTA-STS) that doesn't match how inbound mail actually works.

One correction on the Node side though, because it affects the "we track Node's defaults" reasoning. Read off the running mail container:

# node -p 'require("tls").DEFAULT_CIPHERS'
...:ECDHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA256:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!SRP:!CAMELLIA

That list names 12 suites explicitly and then ends with the HIGH: catch-all, which expands it to 58. Every flagged suite arrives through the catch-all — not one of them is named in Node's own list:

                                 with HIGH:   without
ECDHE-ECDSA-AES256-CCM8             yes         no
ECDHE-ECDSA-ARIA256-GCM-SHA384      yes         no
ECDHE-ECDSA-AES256-SHA              yes         no

So upgrading Node doesn't move this. The list has had the same shape for years, and Node 24 in Cloudron 10 will produce the same test result that Node 22 does today.

And the compatibility argument, while true, covers a narrower set than the whole list. The long tail of old MTAs lives on the CBC-SHA1 suites. ARIA is a Korean national standard and CCM_8 is a short-tag variant from the IoT world — no MTA in the wild speaks only those. Just noting where the observation stands; the trade-off is yours to make.

Reply to Mail app fails the internet.nl mail test on cipher suites on Sat, 08 Aug 2026 09:24:12 GMT

girish — Sat, 08 Aug 2026 09:24:12 GMT

The last time I touched all these ciphers, they started failing left and right in production. In fact, we had to whitelist even TLS 1.1 for a big german provider. The reality is if you want to accept mail, you have to be as open as possible and people get very upset when they are unable to get mail and they get no notification about this. Since this is all at the connection level, it is incredibly hard to surface all this information to the admin and users in some meaningful way. So yeah, best not to touch all this. These are the nodejs defaults (which we keep upgrading. Cloudron 10 has 24.19.0).

$ node -e 'console.log(require("tls").DEFAULT_CIPHERS)'
TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:DHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA256:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!SRP:!CAMELLIA