Debugging Reacher
Last updated
Last updated
The reflex to have when debugging Reacher is to set the -e RUST_LOG=debug flag to Docker. This will show all debug logs useful to pinpoint where the error happened.
If you still don't understand the error after setting that flag, send an email to along with those debug logs.
This only concerns users installing Reacher on a server without using Proxies.
When choosing a server to install Reacher on, you need to make sure that the server itself has port 25 open AND the chosen cloud provider allows outbound port 25 connections on its network.
To test this, there are two methods:
curl (try this first)
telnet (more advanced)
curlPaste the following command in the shell of your server.
telnetPaste the following command in the shell of your server.
Here are details about some of the most well-known providers:
❌ GCP: Port 25 closed, source.
❌ Heroku: Starting from July 2021, Heroku blocks port 25 intermittently according to this document.
"is_reachable": "unknown"?In most cases, if you have a TimeoutError, it means that port 25 is closed. Refer to the questions above about opening port 25.
In other cases, you can enable the RUST_LOG=debug environment variable on your server or on your Docker container. Then, by looking at the logs when performing an email verification, you can debug why is_reachable is unknown. Some example of logs you might find:
IP Blacklisted:
5.7.1 Service unavailable; Client host [<YOUR_IP>] is blacklisted. Visit https://www.sophos.com/en-us/threat-center/ip-lookup.aspx?ip=<YOUR_IP> to request delisting
Your FROM field does not match the reverse DNE
(mxgmx117) Nemesis ESMTP Service not available; No SMTP service;
AWS: Needs an application to open port 25, link to apply (Dec 2020).
Digital Ocean: Your account needs to be 60d old, then you can apply to open port 25 (Mar 2020).
Hetzner: Port 25 open according to unofficial source (Feb 2021), but seems now that you need to request manually.
Linode: Port 25 closed for new accounts, but can be opened if reverse DNS is set up correctly, source (Apr 2022).
OVH: Port 25 open on new instances, but outbound port 25 traffic is monitored to prevent spam (May 2022).
Vultr: Create support ticket to open port 25, source, though recent reports (May 2022) show that they won’t do it anymore.
If you encounter any issue that you don't know how to solve, simply send me an email to .