None of the authentication methods supported by this client are supported by your server.

[arjanvr]

Hello,

This week suddenly a lot of people are having trouble sending email. They get this message while before everything was working fine. Sending using SSL is working fine but when they use no ssl with mail.domainname.nl it returns this error. So nothing changed on their computer.

"None of the authentication methods supported by this client are supported by your server."

Did something change or do i need to make a configuration change somewhere since the clients seem to be configured just fine.

I am confused
Thanks

 

[arjanvr]

My supplier told me to do this:

"Login from whm>>Exim Configuration manager>>Security>> Here you have to turn off this options "Require clients to connect with SSL or issue the STARTTLS command before they are allowed to authenticate with the server.""

which did the trick but is a security risk, did something recently change in cpanel that it does not work without this because it all stopped working just a few days ago? And is there a safe workaround?

 

[cPanelMichael]

Hello,

Before making the change to that option, was the issue affecting email sent via a specific email client, or did you notice this happening for multiple users across different email clients?

Thank you.

 

[arjanvr]

It was for multiple users and as far as i know they are all using some form of outlook

 

[cPanelMichael]

Hello,

Does the SSL certificate installed for this domain name include the "mail" subdomain? If not, you'd need to update the incoming and outgoing mail server name in the email client to reflect only domain.tld instead of mail.domain.tld. Or, ensure the SSL certificate for the domain name is installed through the AutoSSL feature so that it automatically includes mail.domain.tld in the certificate.

Thank you.

 

[arjanvr]

Well the problem was it stopped sending on non-ssl settings so can that be related to the certificate?

 

[cPanelMichael]

Hello,

Could you open a support ticket using the link in my signature so we can take a closer look? You can post the ticket number here so we can update this thread with the outcome.

Thank you.

 

[eugenevdm.host]

Just encountered a similar issue after a WHM to WHM migration. We had the good luck of being able to compare the old system, and a legacy PC that didn't work.

On this PC it has Outlook 2013 and Windows 7. Client won't easily update. Client was using 143 and 25. 465 and 587 gave other similar encryption issue messages.

We tried on another system with Thunderbird and it worked straight away.

Once we updated this setting:

“Require clients to connect with SSL or issue the STARTTLS command before they are allowed to authenticate with the server.” from “On” to “Off”.

The problems went away. Our conclusion is that either Outlook 2013 or Windows 7 doesn't support port 25 without this setting enabled.