Resolved Which e-Mail client authentication method is secure?

[Sebo]

Hi all,

I have a question regarding the security of the different e-Mail authentication methods (DIGEST-MD5 CRAM-MD5 PLAIN LOGIN).
At the moment I'm providing all of them but I want to restrict them to most secure ones.

What I can see from the maillog is, that most clients are using the PLAIN method by default.
Also the email.mobilconfig profile for iPhone and iPad, which is automatically provided by Plesk, is preconfigured with the PLAIN method.

So I'm not sure if it make sense, to disable the PLAIN method.

I assume that DIGEST-MD5 and CRAM-MD5 are more secure than PLAIN and LOGIN but I'm not sure.
I did't find enough information about this.

Hopefully someone has some more insights.

Thanks for you support!

 

[Aytalina]

Hello Sebo,

It all depends on various conditions (if there is a secure connection or not, etc).
You can check:

What is the most secured SMTP authentication type?

Say you have to choose only one among the following authentication types for your own SMTP server: LOGIN, PLAIN CRAM-MD5 DIGEST-MD5 NTLM/SPA/MSN Which one would you recommend for optimal security? ...

security.stackexchange.com

How secure is using CRAM-MD5 for email authentication, when not using an SSL connection?

Background: My current server-provider tells me it's no problem to store the passwords in plain-text in the database, saying he has to do so because they use CRAM-MD5 for email authentication. My b...

security.stackexchange.com

Is DIGEST-MD5 secure if done over HTTPS?

If the DIGEST-MD5 negotiation is done over an HTTPS connection instead of HTTP, does that prevent this list of disadvantages from Wikipedia?: Digest access authentication is intended as a security...

security.stackexchange.com

Our KB article just for your reference:

How to prevent plaintext authentication via IMAP/POP3 and SMTP in Postfix on Plesk server?

Applicable to: Plesk for Linux Question How to prevent cleartext / plaintext authentication via IMAP/POP3 and SMTP in Postfix on Plesk server? Answer Note: If you don't have root access to the P...

support.plesk.com

 

[Sebo]

Hi Aytalina,

thanks a lot for the links.

If I understand right, it is basically OK to have the PLAIN method active as long as you use SSL.

Thanks again!
Sebo