Listmonk not sending to full list

[ntnsndr]

After using Listmonk successfully for a while now, I am running into a strange problem this morning. Two things happened:

Sending authentication error. I have the app set (in the Cloudron backend, under app > Email) to send from newsletter@my.cloudronserver.example. But I was getting an error saying:

550 Authenticated user newsletter@my.cloudronserver.example cannot send mail as newsletter.app@my.cloudronserver.example

In the Cloudron backend, under the main email preferences, I set my.cloudronserver.example to allow masquerading. I tried resending the newsletter, and it seemed to work! But then...

Sending to only part of the list. After the above steps, I got a problem I've never seen before. Listmonk says the campaign I sent is "Finished," but only some of the emails were received. On the Campaigns page, it says:

Sent 501 / 1,311

I don't see any evidence of a problem in the logs, which say:

Jan 21 11:35:59 2025/01/21 18:35:59.167357 manager.go:413: start processing campaign (Start of 2025 (take 2))
Jan 21 11:36:14 2025/01/21 18:36:14.601113 pipe.go:217: campaign (Start of 2025 (take 2)) finished

Can you think of any reason why not all of the messages would be sent? Why it would stop at 501 and consider the process finished? What can I do to send the rest of the messages?

[nebulon]

Did you check with the upstream project? This does not look like a packaging bug but more like an app internal issue.

[ntnsndr]

@nebulon Really? It seems to me that Cloudron is very much involved, since a change on Cloudron changed the app's behavior, and the app is trying to send to a different address than the one specified in Cloudron's management.

Could you say more about your reasoning?

[jdaviescoates]

To me it looks like potentially both. The email address issue certainly seems Cloudron related.

The not sending to whole list could be an upstream issue (unless it's just another example of the IPv6 email sending issues lots of us have been having )

Try adding IPv6 PTR record on your server, enabling IPv6 in Network and then Sync DNS in Domains. Might help?

[nebulon]

Given that you mention that some emails went out, I don't think it is an authentication error, but listmonk for some reason stops after some successful mails. If something around auth or platform settings would be wrong, why would it send out parts of the mails and then stops? Maybe the app internally batches or crashes midway (after the 501s email in this case)?

[girish]

Does listmonk have some setting for rate limits? How fast are emails being sent? Cloudron Email only allows 500 connections per second. That's the only 500 that comes to mind in Cloudron code.

[jdaviescoates]

@girish said in Listmonk not sending to full list:

How fast are emails being sent?

The logs @ntnsndr shared above seem to imply the whole thing took 15 seconds.

Sounds plausible to me the 500 connections a second limit has something to do with it

[ntnsndr]

Yeah. I wonder if it is being caused by Hostinger, the new VPS service I'm using. I'm trying to move email sending from SMTP to an external service. Do you think that could help?

[jdaviescoates]

@ntnsndr said in Listmonk not sending to full list:

Yeah. I wonder if it is being caused by Hostinger, the new VPS service I'm using.

Sounds very plausible.

@ntnsndr said in Listmonk not sending to full list:

I'm trying to move email sending from SMTP to an external service. Do you think that could help?

Very likely IMHO

I use Mailgun with my Ghost (because Ghosts requires that)

Lots of people on here have said good things about https://postmarkapp.com/

[ntnsndr]

I have sadly been planning to use AWS because a) I also need storage for backups and it would be nice to have only one more bill to pay, and b) my university has a contract.