Investigating Multi-Recipient Email Delivery Issues on Cloudron v8.2.4

[IniBudi]

Dear Cloudron Team,

Today, I conducted a test by sending emails simultaneously to multiple addresses such as @gmail.com, @outlook.com, and others. However, when I sent the email via Cloudron’s system, only the first email was successfully received, while the rest did not receive the message.

I then attempted a second test using “reply to all,” but the result was the same—only the first email received the message, and the others did not.

My question is: Is there an error in my server configuration, or is there a bug in Cloudron version v8.2.4? I have tried disabling IPv6 and syncing again, but the result remains unchanged. I also attempted enabling both IPv6 and IPv4 simultaneously, yet the issue persists.

Could you please advise on what steps I should take to resolve this issue?

Thank you for your attention and assistance.
Regards

[p44]

Hi @IniBudi, do you use any external relay email service? Eg. Postmark or similar?

I ask you this to better understand your conf but also because last week I sent same email to two different @gmail.com accounts and one of recipient in CC it seems it didn't received email.

But I'm not sure if is similar to your case.

[IniBudi]

I'd like to confirm that the problem was coming from my 3rd party email relay service. I just disabled it and using my own server without having problem at all.

[p44]

@IniBudi Wich email relay are you using? I think this problem should be better addressed and understood to let have a fix...

This because we're used to use relay servers due to poor IP Vps's reputation...

[IniBudi]

@p44 In the previous setup, I used mailketing SMTP server, after using the Built-in SMTP server. I can send emails to several email addresses simultaneously.

[p44]

@IniBudi Ok, thanks. I hope @girish or @nebulon can have a look of this issue

[nebulon]

Not sure what we should look into here, wasn't it an issue with a 3rdparty provider?

[joseph]

@IniBudi said in Investigating Multi-Recipient Email Delivery Issues on Cloudron v8.2.4:

I then attempted a second test using “reply to all,” but the result was the same—only the first email received the message, and the others did not.

Have you checked the mail event log ? It should have an entry for each outbound email.

[p44]

@nebulon Yes, problems occurred due to a 3rd party provider, but it could depend on Cloudron. This is only a hypothesis, of course, that came to my mind because @IniBudi and I experienced the same issue with two different providers when sending emails with Gmail mailboxes in CC.

[IniBudi]

@joseph I think the problem came from my SMTP provider.

  "message": "Message Queued (BD37BA83-C51B-465E-BB2F-9AF424226800.1)"
}

After change the SMTP using the default server, the problem is solved.

[p44]

@IniBudi @nebulon I can confirm that problem is not related to Cloudron, after I did some sending tests.