Attn chat.deltachatkg.xyz sysop [is blocking SMTP/IMAP ports]

Chatmail Relays
1

To the sysop of chat.deltachatkg.xyz,[1] your relay is blocking the SMTP/IMAP ports. I have a user on my relay attempting to send to someone on your relay and it’s error’ing out in the logs trying to connect. I did a quick verification from a different VPS:

$ cmrelaymon.sh -vr chat.deltachatkg.xyz

==> Testing SMTP: chat.deltachatkg.xyz

* Host chat.deltachatkg.xyz:25 was resolved.
* IPv6: (none)
* IPv4: 188.240.213.123
*   Trying 188.240.213.123:25...
* connect to 188.240.213.123 port 25 from 51.222.86.96 port 51636 failed: Connection refused
* Failed to connect to chat.deltachatkg.xyz port 25 after 436 ms: Could not connect to server
* closing connection #0
curl: (7) Failed to connect to chat.deltachatkg.xyz port 25 after 436 ms: Could not connect to server

==> Testing SMTPS: chat.deltachatkg.xyz

* Host chat.deltachatkg.xyz:465 was resolved.
* IPv6: (none)
* IPv4: 188.240.213.123
*   Trying 188.240.213.123:465...
* connect to 188.240.213.123 port 465 from 51.222.86.96 port 57170 failed: Connection refused
* Failed to connect to chat.deltachatkg.xyz port 465 after 191 ms: Could not connect to server
* closing connection #0
curl: (7) Failed to connect to chat.deltachatkg.xyz port 465 after 191 ms: Could not connect to server

==> Testing IMAP: chat.deltachatkg.xyz

* Host chat.deltachatkg.xyz:143 was resolved.
* IPv6: (none)
* IPv4: 188.240.213.123
*   Trying 188.240.213.123:143...
* connect to 188.240.213.123 port 143 from 51.222.86.96 port 40416 failed: Connection refused
* Failed to connect to chat.deltachatkg.xyz port 143 after 190 ms: Could not connect to server
* closing connection #0
curl: (7) Failed to connect to chat.deltachatkg.xyz port 143 after 190 ms: Could not connect to server

==> Testing IMAPS: chat.deltachatkg.xyz

* Host chat.deltachatkg.xyz:993 was resolved.
* IPv6: (none)
* IPv4: 188.240.213.123
*   Trying 188.240.213.123:993...
* connect to 188.240.213.123 port 993 from 51.222.86.96 port 40394 failed: Connection refused
* Failed to connect to chat.deltachatkg.xyz port 993 after 189 ms: Could not connect to server
* closing connection #0
curl: (7) Failed to connect to chat.deltachatkg.xyz port 993 after 189 ms: Could not connect to server

Port 80 and 443 are working.

[1] there is no QR code invite on your relay site to connect via DC, nor a traditional email

2

I am breaking into this discussion (and you can ask me to create a new topic if you think that’s better) because this problem is what kept me off of running a self-hosted instance for Chatmail.

VPS hosters, as well as home internet providers, may limit traffic on SMTP ports or even block them by default. I tested Delta Chat with a generic email provider, and quickly ran into the same problem.

Also, to me a service protocol that initiates the session with a limited challenge–response before it receives arbitrary data feels somewhat safer to host. If i recall correctly, with SMTP this is not the case.

The Chatmail architecture provides a reasonably secure way to distribute secrets. Could this as well be used to distribute generated login passwords between the relays so they can relay messages using IMAP logins and don’t need SMTP connections?