Do I need Port 25 to be open? Est-ce que j'ai besoin que le port 25 soit ouvert?

Hardware/ Matériel: Raspberry pi4

  • bare-metal armhf
  • Server is running Linux kernel 5.10.11-v7l+
  • Server is running Debian 10.8
  • Server is running YunoHost (testing)
  • App: Secure Scuttlebutt Room Server 2.0.6~ynh3

“Port 25 is not reachable from outside.”
“Le port 25 n’est pas joignable de l’extérieur.”
I found out my ISP blocks this by default.
J’ai découvert que mon FAI bloque ça par défaut.

Do I really need Port 25 for regular operations of my server and app?
Ai-je vraiment besoin du port 25 pour les opérations régulières de mon serveur et de mon application?

I have read that Yunohost will send Admin an email if there are problems with the server, but what about the rest of the operations? Do they require port 25 ?
J’ai lu que Yunohost enverra un e-mail à l’administration en cas de problème avec le serveur, mais qu’en est-il du reste des opérations? Ont-ils besoin du port 25?

What about my Scuttlebutt Room app? Does it require Port 25?
Qu’en est-il de mon application Scuttlebutt Room? A-t-elle besoin du port 25?

My Yunohost installation works well without port 25 being open (it is blocked by my ISP too).
I use the following apps with my installation: Roundcube and Rainloop (for internal/server email only–to/from registered users and from the system; cannot send and receive outside the server); WordPress; Flarum (forum); and Nextcloud.

Port 25 is for the unsecured SMTP protocol. Having it blocked may affect sending emails from the server. It’s up to you to see if that’s too much of an issue. Il not, you can Ignore the warning.

Oh that’s good news! Hope it’s the same for the Scuttlebutt Room app. Right now, nobody can see my Scuttlebutt Room in their SSB app once they’ve connected with it, though, have no idea why, thought maybe it was to do with Port 25, but have no idea. Can’t figure it out.

Right. Can’t the server just send me an email over the local network somehow without using Port 25?

If you only wish to receive the administration emails the server sends to you, you can install the Rainloop or Roundcube apps.

If you do wish to send emails, being on the local network or on the Internet will not change anything. I would configure a SMTP relay, but it comes with limitations and other issues, detailed here: Configure SMTP relay | Yunohost Documentation.

Yes, the server sends me administrative/app-related emails even with port 25 closed. Also, any users with profiles on the server are able to send and receive emails to/from one another using their server email addresses. They cannot send to outside addresses, nor can they receive email from outside addresses. Having the private email universe of the server users group is somewhat useful without having to set anything else up. Roundcube or Rainloop installed on the server makes all of these exchanges simple.

mikaelv, tituspijean : very interesting, thanks for the info. I’ll certainly look into Roundcube or Rainloop. Thanks!

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