<![CDATA[Unable to receive email from external mail services]]>Hello

I have noticed that I can't receive email from external services (like gmail, office365 etc). I mostly use the email service for own specific things (Cloudron apps), and mail sent via Cloudron's delivery works fine. But mail from external service providers doesn't come through. I've tested sending from both gmail.com and live.com addresses. None work.

I ran the Cloudron troubleshooter, and that tells me everything is ok.

[OK]	node version is correct
[OK]	IPv6 is enabled in kernel. No public IPv6 address
[OK]	docker is running
[OK]	docker version is correct
[OK]	MySQL is running
[OK]	netplan is good
[OK]	DNS is resolving via systemd-resolved
[OK]	unbound is running
[OK]	nginx is running
[OK]	dashboard cert is valid
[OK]	dashboard is reachable via loopback
[OK]	No pending database migrations
[OK]	Service 'mysql' is running and healthy
[OK]	Service 'postgresql' is running and healthy
[OK]	Service 'mongodb' is running and healthy
[OK]	Service 'mail' is running and healthy
[OK]	Service 'graphite' is running and healthy
[OK]	Service 'sftp' is running and healthy
[OK]	box v9.1.5 is running
[OK]	Dashboard is reachable via domain name
[WARN]	Domain my.domainename expiry check skipped because whois does not have this information

Here's the log from an undelivered mail sent from a Google account. I chose this to test an n8n workflow with two mail address recipients, one gmail address and one address for my Cloudron. I know the mail is sent, because I received to email addressed to my gmail account, but the copy sent to my Cloudron domain (self hosted) is undelivered. I have tried to anonymize the headers by removing the mail addresses, domain name and ip address. Let me know if you need these:

Reporting-MTA: dns; googlemail.com
Arrival-Date: Wed, 01 Apr 2026 03:34:41 -0700 (PDT)
X-Original-Message-ID: <CAG-=ztFbapQFcHFM3-5RFk3UNXteT+y-zLURxVg2qt5E3xGjbQ@mail.gmail.com>

Final-Recipient: rfc822; my-e-mail@cloudron-hosted-domain
Action: delayed
Status: 4.4.1
Diagnostic-Code: smtp; The recipient server did not accept our requests to connect. For more information, go to https://support.google.com/mail/answer/7720
[cloudron.domain.address. cloudron.domain.ip: timed out]
Last-Attempt-Date: Thu, 02 Apr 2026 06:07:53 -0700 (PDT)
Will-Retry-Until: Sat, 04 Apr 2026 03:34:41 -0700 (PDT)
ARC-Seal: i=1; a=rsa-sha256; t=1775135213; cv=none;
       d=google.com; s=arc-20240605;
       b=bL/6dDqeqK2qYkXqqe7fYUCBrZ2b0+SmUG0S2EMaOIbX97QvtexoqsyFJRFMZRBViL
        Cxllz7/WqGTLVskzbkErO+t23tScVLypdXOHxWh/DIgy0PJKcodTfjX+LnFy0SBS+kWw
        494rA1ocmKFgS+U+3dFJZ046eLy5bL8sM7bqplCLFzQVyyVBkcjtZOAebsV+E7EgJ/VS
        Fxk/rbxKVWWAeT7m9VTZLY++lEU7qtOG4DLsnnEXaa6cSzez5usyz6RmS8gnk5L6/6j+
        mV5Vk8AZHCvOyaa0ZXf0SXqiKEnv7CvbZWbU8wwMGauvfoaZ5lSuTbFoirP1rAushlq3
        gF1Q==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20240605;
       h=to:subject:message-id:date:from:mime-version:dkim-signature;
       bh=hOd3S/vxaC77xcBp+F70rioo4lFCYJ1j1z6r0u3/2LA=;
       fh=xFLExUQpO7iut+1J5YZCxMf6a4gpJhZadTj6ynd8yr4=;
       b=lS2L/KeL3n1HPprQQMYFef4lrIIiyL6TU17RM76kHDYaSmXSndk754HTgEfi2kvmgh
        rfoJs44QsXpejs8rXMNaDtT/HcL8gba5w2W58TiF2rDcNsISpCO1a5S2RTbEKarN9mLE
        pQNsqeCtxO9M25+SqcaoO6lz79zex8FeSV5IrjpiVtOQcRCg6l25rSXYDdbmRO1XhpCQ
        hoS6zpvjQamPmE2bSCBhyvFd2yHZWpzJn5kBcdrQ1EGs4LxTD9X5OkuQMifa2Ren9PxP
        dCAekKNVwZb3CPNEUOpXtkISgLeY5hv714snz8WTKLqynPGV8r6BAd5rqjsLmkiLjWq6
        dH8g==;
       darn=my.domain
ARC-Authentication-Results: i=1; mx.google.com; arc=none
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
       d=google.hosted.domain; s=google; t=1775135213; x=1775740013; darn=my.domain;
       h=to:subject:message-id:date:from:mime-version:from:to:cc:subject
        :date:message-id:reply-to;
       bh=hOd3S/vxaC77xcBp+F70rioo4lFCYJ1j1z6r0u3/2LA=;
       b=SHxyZCo8N1GX8ZqRfHY10Z5apx14xqJ7zQUYF/rxBnWvjr0tXDmwzQbLa5vFG//IIH
        Pl9r5NImQRGPgbirVVNd8/3Hbo+LgsROjPqwuu3YukQ3Zlo7pyCxocZNd5D/mTXtPMu/
        AqQnNPczHwFYCtIyLTzVyYgM8WZlQ8tNxk0pPSnem+H0El/oSmJ2mTohcVj3ACFtvjHb
        ECVolIYiIYsWeZpZtUDhDcDzvHqAMUM8Qe/vFeQjEYT7SjchAZjSjb8lkQGim4JJ+r4y
        PDHo3A3YGnxOXkKUm4AavtnRZtIFqCuvv4Pg24D8Ml3hWkINQow48xrOZkyYn5OocMeh
        wFTQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
       d=1e100.net; s=20251104; t=1775135213; x=1775740013;
       h=to:subject:message-id:date:from:mime-version:x-gm-gg
        :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to;
       bh=hOd3S/vxaC77xcBp+F70rioo4lFCYJ1j1z6r0u3/2LA=;
       b=shtb79Z9iseewp554cHd1jfWqOickpNfWnHTnO5IGh0dgko8Nfj/EI8zmaW6UlXSb5
        tnMhx+CE9mas89SCuioq8TpRgOYHarxeF3vdlHqki/cSODNvoP6VbzI5FcCuxHmGjA+i
        bP+L3O5MMuIughyH5zReONBJiKsoMFxdoh0GpCUG+r4Q9Fwkh3iC6eKxr1jN/bKTGofh
        T9K2lBlZIU2g1HkTj5nf+C+azZYRQLFvDCGZwBTYUxo/vkK2/8mJnXaoBoDQ79/zb29o
        l4fLbJQukUmpe25jw4MnWyiTMfSfnBGCXlN0nQIwxFi/Ovl/2AbdQ+ey/b9zmZu/+uDe
        PnYQ==
X-Forwarded-Encrypted: i=1; AJvYcCVHPy6AG3BpmqV4UzUfuT5iuVHFlhDEiw67SG0HVDTL5pTpvx0+RNWxUfbItaHLV9Y48mlgT4UK@my.domain
X-Gm-Message-State: AOJu0YxMaVMWC9yzoma0H7cVT3D5S6wuxAm2z/FXkd/6Yr45xK9cvMHG
	0utzZjeduKK1eXCcYQbbWMkvuNawT7nPJu1kc4YsGzFpbQdXp/i9CqaKkNGHsz2LGWph2ERd6h1
	nu1MIIsmpvBGO2cNDfbkkxFba2JLDKcJJ1Aji1bCfLYZ+CVUCsRxh8R8=
X-Gm-Gg: ATEYQzwjm2u9KIVKbehrz1nlfPFgK9pyVjVxBr0v6w4VuIDgcMdOaclozhRuMBJBb5R
	664/BcRqKYMwgihz+P3kLuwU2C3GuYrMuY2rEZJZ/I8Q/yMry+ex4FOtR7ta9+LAT7OoL6m6vp5
	E3y4HSbSAX3BTPRBkGXmJb/ByPcHYB7xDJSjVsRX1ThrCVvfm2LzZqA/yPxrW6iClEi6MEQkd9x
	EnyB9Z+jr8SZ0kazyUCp5W8L7mv2fXaCEx3xB+EO8KizuXjk44Fj3QxbYNX11b2IUE7X5YyvonQ
	AmLnU8p7
X-Received: by 2002:a05:6512:1388:b0:5a2:b514:4fbb with SMTP id
2adb3069b0e04-5a2c2109806mr1380632e87.11.1775039681610; Wed, 01 Apr 2026
03:34:41 -0700 (PDT)
Received: from 1066260365263 named unknown by gmailapi.google.com with
HTTPREST; Wed, 1 Apr 2026 03:34:40 -0700
Received: from 1066260365263 named unknown by gmailapi.google.com with
HTTPREST; Wed, 1 Apr 2026 03:34:40 -0700
MIME-Version: 1.0
From: oddgeir@google.hosted.domain
Date: Wed, 1 Apr 2026 03:34:40 -0700
X-Gm-Features: AQROBzC58mMCN5sKP30LQKYOrMJIgzCMHAJUt1i5vFiZFe9Vyyf_psEcP_buESA
Message-ID: <CAG-=ztFbapQFcHFM3-5RFk3UNXteT+y-zLURxVg2qt5E3xGjbQ@mail.gmail.com>
Subject: n8n Workflow Failure: Example Workflow
To: my-email@gmail.com, my-e-mail@cloudron-hosted-domain
Content-Type: text/plain; charset="UTF-8"

I plan on trying to troubleshoot tomorrow (I get family over for an Easter gathering now), so any help/tips will be much appreciated.

]]>https://forum.cloudron.io/topic/15339/unable-to-receive-email-from-external-mail-servicesRSS for NodeMon, 05 Oct 2026 14:52:40 GMTThu, 02 Apr 2026 13:28:07 GMT60<![CDATA[Reply to Unable to receive email from external mail services on Sat, 04 Apr 2026 15:33:09 GMT]]>@robi I believe that's because the firewall drops the packages. So Google's servers just don't receive a response (timeout).

]]>https://forum.cloudron.io/post/122912https://forum.cloudron.io/post/122912Sat, 04 Apr 2026 15:33:09 GMT<![CDATA[Reply to Unable to receive email from external mail services on Fri, 03 Apr 2026 16:21:22 GMT]]>Yay!

Odd that gmail didn't receive bounced messages from the firewall

]]>https://forum.cloudron.io/post/122890https://forum.cloudron.io/post/122890Fri, 03 Apr 2026 16:21:22 GMT<![CDATA[Reply to Unable to receive email from external mail services on Fri, 03 Apr 2026 10:11:44 GMT]]>

odie said:

Hello @james and @robi
Thank you for your follow-ups. I will try to clarify.

My Cloudron doesn't accept incoming emails from Google/Gmail. The e-mail bounces back to Google (Gmail) instead of being delivered.

I included the n8n logs, as they were done on a workflow I have setup using the Gmail node, and where I set both a Gmail and my Cloudron instance as recipients. The mail was received by my Gmail account, but was undelivered to my Cloudron box.

I will try to simplify: Mail sent from Gmail times out - it never reaches my Cloudron box at all.

Yesterday evening, I was able to test sending e-mails from Live (Microsoft) and Proton to my Cloudron box, and both of these go through. So it seems it is only mail from Gmail that my Cloudron box refuses to accept.

The "extra weird" thing is that, for my outgoing e-mails, I use Google's servers as outgoing SMTP. Despite this, e-mails sent with my Cloudron box are received by the Cloudron box, but not when they are sent from a Google account (this applies both to e-mails sent from Google's Gmail service and from Google hosted Workspace accounts).

It seems something on my Cloudron box is refusing to accept mail sent from Google.

Is there a way to reset Cloudron's spam filter training? For testing purposes, I have already disabled Spamhouse (Mail ACL), and there are 0 addresses on the blocklist in my spam filtering.

Thank you very much for providing assistance!

I managed to figure it out. The problem wasn't Cloudron related. I have a firewall in front of the Cloudron that is "learning", and it has at some time decided to pick up (and block) traffic from Google's servers on port 25. Once I fixed that, I received the emails.

Thank you for all your attempts at helping, and apologize for making you think about issues that I should have discovered earlier (I've tried fixing it on my Cloudron box for more than a week, and it just occurred to me now that the solution might exist elsewhere...).

]]>https://forum.cloudron.io/post/122880https://forum.cloudron.io/post/122880Fri, 03 Apr 2026 10:11:44 GMT<![CDATA[Reply to Unable to receive email from external mail services on Fri, 03 Apr 2026 07:21:25 GMT]]>Hello @james and @robi
Thank you for your follow-ups. I will try to clarify.

My Cloudron doesn't accept incoming emails from Google/Gmail. The e-mail bounces back to Google (Gmail) instead of being delivered.

I included the n8n logs, as they were done on a workflow I have setup using the Gmail node, and where I set both a Gmail and my Cloudron instance as recipients. The mail was received by my Gmail account, but was undelivered to my Cloudron box.

I will try to simplify: Mail sent from Gmail times out - it never reaches my Cloudron box at all.

Yesterday evening, I was able to test sending e-mails from Live (Microsoft) and Proton to my Cloudron box, and both of these go through. So it seems it is only mail from Gmail that my Cloudron box refuses to accept.

The "extra weird" thing is that, for my outgoing e-mails, I use Google's servers as outgoing SMTP. Despite this, e-mails sent with my Cloudron box are received by the Cloudron box, but not when they are sent from a Google account (this applies both to e-mails sent from Google's Gmail service and from Google hosted Workspace accounts).

It seems something on my Cloudron box is refusing to accept mail sent from Google.

Is there a way to reset Cloudron's spam filter training? For testing purposes, I have already disabled Spamhouse (Mail ACL), and there are 0 addresses on the blocklist in my spam filtering.

Thank you very much for providing assistance!

]]>https://forum.cloudron.io/post/122871https://forum.cloudron.io/post/122871Fri, 03 Apr 2026 07:21:25 GMT<![CDATA[Reply to Unable to receive email from external mail services on Thu, 02 Apr 2026 17:38:22 GMT]]>This is at least 2 different issues:

  1. failures from Gmail to ocano domain (which should have bounces at Gmail)

  2. self-hosted n8n to Gmail (which works reportedly) AND a local ocano mailbox (which doesn't)

]]>https://forum.cloudron.io/post/122854https://forum.cloudron.io/post/122854Thu, 02 Apr 2026 17:38:22 GMT<![CDATA[Reply to Unable to receive email from external mail services on Thu, 02 Apr 2026 15:54:51 GMT]]>Hello @odie

@odie said:

but the copy sent to my Cloudron domain (self hosted) is undelivered

So the issue is only when you send from Cloudron and CC your own Cloudron?
I am a little confused by the set up and could need some clarification.

]]>https://forum.cloudron.io/post/122848https://forum.cloudron.io/post/122848Thu, 02 Apr 2026 15:54:51 GMT