CRAM-MD5 authentication failing

  • victorkun

    (@victorkun)


    1 week ago

    When I put in the suggested code to force AUTH LOGIN, the mail gets sent/received properly.

    But without it, I get the following :
    ===========================================================
    2025-02-27 01:19:39 CLIENT -> SERVER: STARTTLS?
    ?2025-02-27 01:19:39 SERVER -> CLIENT: 220 2.0.0 Ready to start TLS?
    ?2025-02-27 01:19:39 CLIENT -> SERVER: EHLO our.wordpress.server?
    ?2025-02-27 01:19:39 SERVER -> CLIENT: 250-our.domain250-PIPELINING250-SIZE 35840000250-VRFY250-ETRN250-AUTH PLAIN LOGIN DIGEST-MD5 CRAM-MD5 NTLM GSSAPI GSS-SPNEGO250-AUTH=PLAIN LOGIN DIGEST-MD5 CRAM-MD5 NTLM GSSAPI GSS-SPNEGO250-ENHANCEDSTATUSCODES250-8BITMIME250-DSN250 SMTPUTF8?
    ?2025-02-27 01:19:39 CLIENT -> SERVER: AUTH CRAM-MD5?
    ?2025-02-27 01:19:39 SERVER -> CLIENT: 334
    <something hashed>?
    ?2025-02-27 01:19:39 CLIENT -> SERVER: [credentials hidden]?
    ?2025-02-27 01:19:41 SERVER -> CLIENT: 535 5.7.8 Error: authentication failed: <something hashed>?
    ?2025-02-27 01:19:41 SMTP ERROR: Username command failed: 535 5.7.8 Error: authentication failed: <something hashed>??
    ?SMTP Error: Could not authenticate.?
    ?2025-02-27 01:19:41 CLIENT -> SERVER: QUIT?
    ?2025-02-27 01:19:41 SERVER -> CLIENT: 221 2.0.0 Bye?
    ?2025-02-27 01:19:41 Connection: closed?
    ?SMTP Error: Could not authenticate.
    ===========================================================

    Does plugin WP Mail SMTP just not support CRAM-MD5? Sorry, I’m a newbie, so maybe I’m asking/saying the wrong things…but all I know is using default setup, mail fails.

    I hope someone can point me in the correct direction for resolution…

Viewing 3 replies - 1 through 3 (of 3 total)
  • Plugin Support Patrick

    (@paddyam)

    Hey @victorkun,

    To clarify further, WP Mail SMTP relies on WordPress’s built-in PHPMailer, which attempts authentication using the following methods in order:

    • CRAM-MD5
    • LOGIN
    • PLAIN
    • XOAUTH2

    Based on your description, if the SMTP server isn’t configured to accept the authentication method, the connection will fail. However, using the snippet should help force the option and have the emails working as expected.

    I hope this clarifies the issue!

    • This reply was modified 5 days, 18 hours ago by Patrick.
    Thread Starter victorkun

    (@victorkun)

    Thanks for the reply!
    As I said, I’m no expert.
    I saw references to PHP Mailer and fixes, but I was thinking WP Mail SMTP was using it’s own mail programs and kind of dismissed them.
    Now that I know WP SMTP Mail actually does use PHP Mailer, it gives me more knowledge to work with…

    Much Mahalo’s!

    Thread Starter victorkun

    (@victorkun)

    Do you think there might be a possibility that it might be an issue on our WordPress server?
    Everything is up to date : patched RedHat 9.5, and its supported PHP 8.2.27, latest WordPress, and latest plugin version…

    Is there a way to test outside of WordPress? That way I have supporting tests that show it’s not the app (WordPress nor WP Mail SMTP)

Viewing 3 replies - 1 through 3 (of 3 total)
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