Hey Daniel, 

Thanks for reaching out with this issue. What are you using for the auth method?

If it's NTLM type change it to Encrypted password or something else. In the last version, we used to advertise that we do not support NTLM on some protocols. Can you check and see what the administrative logs say when you try to login? Please also try another authentication method like Encrypted Password for instance. 

Let me know if this helps. 

Kind Regards, 

Hello Zach,

many thanks for your reply. Yes those IMAP connection attempts are with SSL/TLS and encrypted password as the authentization options in the the Thunderbird client. We do not support any NTLM related authentication anymore for some time and never even had it with SmarterMail.

I try checking the logs, yes.

I was just wondering, since this is about the only one account (admin) and Thunderbird client, that something has changed in the latest release, maybe a security feature or anything, only for this admin account. Or it may be a Thunderbird bug, of course, since it works well in Outlook and Android mobile client.

Thanks, Dan.

Hello, 

I have submitted a BUG report for this issue. Thank you

Tony,

I can confirm this bug with AUTH CRAM-MD5 for Primary Domain Administrators on a domain, but we are only seeing it with SMTP. The error in the detailed SMTP logs is as follows:

Exception: String reference not set to an instance of a String.
[2023.05.01] Parameter name: s   at System.Text.Encoding.GetBytes(String s)   at MailService.TcpServerLib.SMTP.SMTPSession.CramMD5Validation(Domain domain, User user, String digest, String md5Hash)   at MailService.TcpServerLib.SMTP.SMTPSession.ProcessAuthData(String authData)11:46:31.232 [12772902] rsp: 535 Authentication failed

We had every website begin to fail SMTP Authentication when sending email through SmarterMail after installing the latest build (since our customer's websites by default use the initial Primary Domain Administrator credentials for SMTP upon creation of the domain and website in MSPControl). Also saw it happen with all Apple users although with them we were able to set their Authentication method to "Password" or "Plaintext" to work around the issue.

Hello again,

seems the issue (apparently a bug) has been fixed in latest build 8524 that we installed today. So thank you, SmarterTools team.

Thanks, Dan.