Authentication failed / Relaying error

Question: I successfully sent a message last week. Yesterday, I changed one word in the copy of the text and tried to resend it. I got errors. I did not revise settings. I subsequently took an old, successfully sent message, changed the recipient list to just be me and sent that message. I got the same error. Any insights?

Here’s the copy of the delivery log:

[01] 1/29 07:58:56 ~ Opening connection for delivery...
[01] 1/29 07:58:56 ~ Connecting to **********.com for POP authentication...
[00] 1/29 07:58:56 +OK Dovecot ready.
[00] 1/29 07:58:56 > USER *********
[00] 1/29 07:58:56 +OK
[00] 1/29 07:58:56 > PASS *********
[00] 1/29 07:58:59 -ERR [AUTH] Authentication failed.
[00] 1/29 07:58:59 > QUIT
[00] 1/29 07:58:59 +OK Logging out
[01] 1/29 07:58:59 ~ Connecting to smtp.********.net Port:25
[01] 1/29 07:58:59 ~ Connected
[01] 1/29 07:58:59 220 *************.net ESMTP server ready
[01] 1/29 07:58:59 > HELO [10.0.1.2]
[01] 1/29 07:58:59 250 ***********.net hello [**.**.**.**], pleased to meet you
[01] 1/29 07:58:59 > MAIL FROM:<*********@*****.com>
[01] 1/29 07:58:59 250 2.1.0 <*********@*****.com> sender ok
[01] 1/29 07:58:59 > RCPT TO:<*********@******.com> [1/1]
[01] 1/29 07:58:59 550 5.1.1 <*********@******.com> relaying not allowed

Answer: You are using an outdated authentication scheme, you should try ESMTP rather than POP. We provide the POP authentication for old servers but nowadays most servers will require the ESMTP authentication instead.

As a result, you get an 'Authentication failed' error and later your messages are not accepted for delivery with a relaying not allowed' error.

I recommend you to have a look at those two short videos, the first explains how to enter the server settings into MaxBulk Mailer and the second one explains how to read the MaxBulk Mailer connection log: