@KYI - I think you are reffering to the content of the emails, where some emails are base64 encoded while others are not?
If so, then this is just the encoding type of the email and mailwizz does not use base64 encode but quoted-printable.
@KYI
Do u want to Encrypt Connection of PMTA to GMAIL/YAHOO etc???
# openssl req -new -x509 -days 3650 -nodes -out "/etc/ssl/private/pmta.example.com.cert" -keyout "/etc/ssl/private/pmta.example.com.key"
# cat /etc/ssl/private/pmta.example.com.cert /etc/ssl/private/pmta.example.com.key > pmta.example.com.pem
#SSL
smtp-server-tls-certificate /etc/ssl/private/pmta.example.com.pem
smtp-listener 0.0.0.0:2525 tls= yes
<domain *>
.....
.....
.....
use-starttls yes
</domain>
<source 127.0.0.1>
.....
.....
.....
allow-starttls yes
</source>
smtp-listener 0/0:2524
.
.
.
<domain *>
...
...
type smtp
use-starttls yes
require-starttls no
...
...
</domain>
smtp-listener 0/0:25252
.
.
.
<domain *>
...
...
type smtp
use-starttls yes
require-starttls no
...
...
</domain>
Connected to smtp://mail.design-melt.com:25252/?starttls=always
<< 220 port24.revtonic.com ESMTP service ready
>> EHLO [172.31.11.248]
<< 250-port24.revtonic.com says hello
<< 250-ENHANCEDSTATUSCODES
<< 250-PIPELINING
<< 250-CHUNKING
<< 250-8BITMIME
<< 250-AUTH CRAM-MD5 PLAIN LOGIN
<< 250-AUTH=CRAM-MD5 PLAIN LOGIN
<< 250-XACK
<< 250-SIZE 0
<< 250-VERP
<< 250-SMTPUTF8
<< 250 DSN
ERROR: The SMTP server does not support the STARTTLS extension.
@ClintonLee83 did you get that error after selecting the protocol as "STARTTLS" on the Mailwizz app?