Send Test Email using wrong server

I have been struggling with this plugin all day today. While the connectivity test works, and the diagnostic works and shows the remote SMTP server in the settings, the send test email does not work.

Instead, it tries to connect to the local exim instance and then it fails to authenticate because it’s using the credentials for the remote server.

Any ideas why the send email test would not be connecting to the remote server?

OS: Linux centos1.xxxxx.com 3.10.0-229.el7.x86_64 #1 SMP Fri Mar 6 11:36:42 UTC 2015 x86_64
PHP: Linux 5.5.30 C
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=Yes, zlib_encode=Yes
WordPress: 4.3.2 en_US UTF-8
WordPress Theme: TheFox
WordPress Plugins: LayerSlider WP, Contact Form 7, Custom Facebook Feed, Image Widget, WPBakery Visual Composer, Postman SMTP, Revolution Slider, TheFox Custom Post, Social Media and Share Icons (Ultimate Social Media), WP User Avatar
WordPress wp_mail Filter(s): wp_staticize_emoji_for_email
Postman: 1.7.2
Postman Sender Domain (Envelope|Message): domain.com | domain.com
Postman Prevent Message Sender Override (Email|Name): No | No
Postman Active Transport: SMTP (smtp:tls:plain://mail.domain.com:587)
Postman Active Transport Status (Ready|Connected): Yes | Yes
Postman Deliveries (Success|Fail): 0 | 1

Please realize that for log safety, I’ve replaced the actual domainname with “domain”.

Yet, when you send the test email, instead of going to mail.domain.com, you will see that it’s connecting to the local exim install

smtp:tls:plain://mail.domain.com:587

220-centos1.xxxxxx.com ESMTP Exim 4.86 #2 Wed, 27 Jan 2016 14:15:23 -0500
220-We do not authorize the use of this system to transport unsolicited,
220 and/or bulk e-mail.
EHLO localhost
250-centos1.xxxxxxx.com Hello localhost [10.10.0.12]
250-SIZE 52428800
250-8BITMIME
250-PIPELINING
250-AUTH PLAIN LOGIN
250-STARTTLS
250 HELP
STARTTLS
220 TLS go ahead
EHLO localhost
250-centos1.xxxxxx.com Hello localhost [10.10.0.12]
250-SIZE 52428800
250-8BITMIME
250-PIPELINING
250-AUTH PLAIN LOGIN
250 HELP
AUTH PLAIN
334
[password removed]
435 Unable to authenticate at present

https://ww.wp.xz.cn/plugins/postman-smtp/