550-Please turn on SMTP Authentication in your mail client

noname2020

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Hi.

I am on a shared webspace of hosting company hostens, which is using cpanel.

I use mail via IMAP and from time to time i get from customers the information that they have problems to answer on my mail.

When they want to answer on my mail directly they get an error. When they send me a new mail, its not a problem.

The error message is:
This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

[email protected]
host lt2.eu.cpanel.hostens.cloud [62.77.153.110]
SMTP error from remote mail server after RCPT TO:<[email protected]>:
550-Please turn on SMTP Authentication in your mail client. mx1a.serveriai.lt
550-[79.98.24.211]:47606 is not permitted to relay through this server without
550 authentication.
Reporting-MTA: dns; mx1a.serveriai.lt

Action: failed
Final-Recipient: rfc822;[email protected]
Status: 5.0.0
Remote-MTA: dns; lt2.eu.cpanel.hostens.cloud
Diagnostic-Code: smtp; 550-Please turn on SMTP Authentication in your mail client. mx1a.serveriai.lt
550-[79.98.24.211]:47606 is not permitted to relay through this server without
550 authentication.

I searched and read already in many threads, but couldnt find a solution.

Can someone help or has ideas, how i could solve the problem?

Greets
 
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noname2020

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Additional:
If i look into "Track Delivery" in the section "Email" it shows me from the last days lots of messages with a warning sign, which got rejected.

If i look into "EMail Deliverability" it shows me "Problems Exist (SPF) on addtional domain in cpanel. Is this causing the problem?

Greets
 

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cPRex

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Hey there! We have details about the SMTP authentication error here:


Can you check out that tutorial and see if that helps your situation?

For the SPF issue, it would depend on if your local server is managing the DNS for your domain. If so, I would expect the records created in cPanel to work well in DNS, but you may need to contact your hosting provider or datacenter to find out more about how your DNS is configured.

Let me know if you have any questions on either of those issues.
 

noname2020

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Hi.

i am on a shared webspace, so i have no access to this points you mentioned in your answer :-/

I contacted already the server company and asked for help, but they say, everything is functioning wihtout any problems :-/ But i still get every few days mails rejected with the problems from the first post of this thread.

Track Delivery shows me over the last 5 days that more than 10 emails got rejected....

Greets
 

cPRex

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Thanks for the additional details. Could you send me a private message with your domain name so I can do some more testing on my end? Your options are a bit limited without root access, but I'd like to check the DNS on my end and see what I find.
 

noname2020

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Ok. Thanks for the info.

I will monitor the issue and hope i can find a solution when it happens again. The strange thing is, that is only sometimes and not always.
Also one client told me, he couldnt answer on my mail, but when he sends me a new mail, he had no problems sending it to me.

Greets
 

cPRex

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Since the issue doesn't happen consistently, that does sound like it would be something on the mail client side and not the server side, as it is unlikely a server setting would be frequently changing to cause this.

The host may also be able to check /var/log/maillog to see the authentication session when this issue happens if you can provide them with an accurate timestamp of one of the incidents.
 

noname2020

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" Since the issue doesn't happen consistently, that does sound like it would be something on the mail client side and not the server side, as it is unlikely a server setting would be frequently changing to cause this. "
--> Exact this is making it so difficult to find out, whats causing it. I still struggle with it.

" The host may also be able to check /var/log/maillog to see the authentication session when this issue happens if you can provide them with an accurate timestamp of one of the incidents. "
--> Thanks for the info. Next time when it happens, i will tell the host to look into the maillog.

Can i also see the maillog on my shared hosting cpanel account? the timestamp from the last time, when the problem appeared, i have. Its 3 days ago.

Greets
 

noname2020

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Yesterday it happened again. After i contacted the support, they told me: The relay server is disabled now.
After that i had been able to receive emails again. I dont know, if this is forever now or not.

They also told me:
Then relay is enabled on the server when IP address is blacklisted somewhere. We have abuse team that monitors all the servers and if they see that our hosting packages are used for spamming or mass making, we opened the abuse tickets. However, the servers are shared, so it might be that IP address will be blacklisted somewhere, so when it happens, we enable on the server a relay until the IP address will be delisted.

They also said, it maybe related to the filter - i dont know if this can be true. I use SpamExperts in Cpanel and have already whitelisted the emails/domain, which had always been making problems every few days. But the problems also happened, after i had been whitelisting them.

I really would like to understand where the problem is? Is it because its a shared hosting and when their IPs are getting maybe from an other customer abused, that they open a relay on the server to block all ingoing/outgoing emails on this ip on that server?

Greets
 

InterServed

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Hello,

Something that i would look for (Hoster/root access):

If you have CSF firewall installed, then check on the firewall configuration if SMTP_BLOCK is enabled. If this is enabled, then you need to make sure that you disable the Restrict outgoing SMTP option from WHM Tweak settings page, and configure the cPanel accounts that should not be restricted on the CSF firewall SMTP_ALLOWUSER.

If Restrict outgoing SMTP to root, exim, and mailman (FKA SMTP Tweak) is enabled on WHM Tweak settings, then you may want to remove the restriction for certain cPanel user

Note: replace value with UID of the cPanel account you wish to allow (type "id cpanelusername"), and the name of the account.

Code:
[ ! -d "/var/cpanel/smtpmailgidonly" ] && mkdir "/var/cpanel/smtpmailgidonly"
cat <<'EOF' >/var/cpanel/smtpmailgidonly/conf.yaml
---
  RULES:
    -
      type: "uid"
      value: 1111
      name: "cPanelAccountToAllow"
EOF
/usr/local/cpanel/scripts/smtpmailgidonly --refresh
Unfortunately this may not be of help to you, as you are on a shared hosting plan and no root access. But it may help others who encounter the same problem but having root access.
Maybe you can ask your hosting support if they can check if your cpanel account is allowed to remotely connect on smtp 25 (bypassing the most likely enabled restriction).
 
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cPRex

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I really would like to understand where the problem is? Is it because its a shared hosting and when their IPs are getting maybe from an other customer abused, that they open a relay on the server to block all ingoing/outgoing emails on this ip on that server?
This sounds like the most likely scenario with the situation you've described. If they are having to change the relay server when this happens, that sounds like the best explanation.

Since you're on a shared system, there isn't much that you can do as you're at the mercy of the server admin, and to some extent, the other users.
 

noname2020

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@InterServed
Thanks for your tips. Especially i will ask my hosting company to check, if my cpanel account is allowed to remotely connect on smtp25.

@cPRex
"This sounds like the most likely scenario with the situation you've described. If they are having to change the relay server when this happens, that sounds like the best explanation.
Since you're on a shared system, there isn't much that you can do as you're at the mercy of the server admin, and to some extent, the other users."

So what would i have to do, to end this scenario? Would i need to look for a vServer or Root Server? What is there important to look for? That i get root access? Should i look to get also an dedicated IP on such a server?
Because i want also to prepare right in time, that i know what to do, when the problem is not possible to solve.

Thanks for all the help!

Greets
 

cPRex

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Having a server with full root access would prevent the actions of other users from causing negative effects on the machine. On a shared server, if one account is able to send spam, even for a brief period, it's possible the IP gets blocked and then getting that reputation back is difficult. If you control everything though, it is far less likely for that to happen, and easier for your or your host to resolve if it does.
 

noname2020

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Thank you very much for your answer again. Ok, then i will give it a last try with the shared webhosting company and if this fails again, i will switch over to a root server.

Greets
 
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