aden@amckinley:~$  cat sample_email.txt | msmtp --debug -a amckinley aden.mckinley@gmail.com
ignoring system configuration file /etc/msmtprc: No such file or directory
loaded user configuration file /home/aden/.msmtprc
using account amckinley from /home/aden/.msmtprc
host = smtp.zoho.com
port = 587
proxy host = (not set)
proxy port = 0
timeout = off
protocol = smtp
domain = localhost
auth = choose
user = aden@amckinley.me
password = *
passwordeval = (not set)
ntlmdomain = (not set)
tls = on
tls_starttls = on
tls_trust_file = (not set)
tls_crl_file = (not set)
tls_fingerprint = (not set)
tls_key_file = (not set)
tls_cert_file = (not set)
tls_certcheck = off
tls_min_dh_prime_bits = (not set)
tls_priorities = (not set)
auto_from = off
maildomain = (not set)
from = aden@amckinley.me
add_missing_from_header = on
add_missing_date_header = on
remove_bcc_headers = on
dsn_notify = (not set)
dsn_return = (not set)
logfile = (not set)
syslog = (not set)
aliases = (not set)
reading recipients from the command line
<-- 220 mx.zohomail.com SMTP Server ready August 15, 2017 7:25:52 PM PDT
--> EHLO localhost
<-- 250-mx.zohomail.com Hello localhost (159.203.4.58 (159.203.4.58))
<-- 250-STARTTLS
<-- 250 SIZE 53477376
--> STARTTLS
<-- 220 Ready to start TLS.
TLS certificate information:
    Owner:
        Common Name: *.zoho.com
    Issuer:
        Common Name: thawte DV SSL CA - G2
        Organization: thawte\, Inc.
        Organizational unit: Domain Validated SSL
        Country: US
    Validity:
        Activation time: Thu 01 Sep 2016 12:00:00 AM UTC
        Expiration time: Sat 01 Sep 2018 11:59:59 PM UTC
    Fingerprints:
        SHA1: 10:72:1E:8E:C1:05:77:F2:27:9B:0E:12:14:27:C5:96:0F:71:2F:B6
        MD5:  B5:F9:8A:60:4D:45:1B:7C:04:74:62:A3:49:4A:30:18
--> EHLO localhost
<-- 250-mx.zohomail.com Hello localhost (159.203.4.58 (159.203.4.58))
<-- 250-AUTH LOGIN PLAIN
<-- 250 SIZE 53477376
--> AUTH PLAIN AGFkZW5AYW1ja2lubGV5Lm1lAEBkM25NY2s3N3h4Z2I4Zg==
<-- 235 Authentication Successful
--> MAIL FROM:<aden@amckinley.me>
<-- 250 Sender <aden@amckinley.me> OK
--> RCPT TO:<aden.mckinley@gmail.com>
<-- 250 Recipient <aden.mckinley@gmail.com> OK
--> DATA
<-- 354 Ok Send data ending with <CRLF>.<CRLF>
--> Date: Wed, 16 Aug 2017 02:25:52 +0000
--> From: aden@amckinley.me
--> \ To: aden.mckinley@gmail.com
--> \ Subject: Hello World
--> \
--> \ This email was sent using MSMTP.
--> .
msmtp: the server sent an empty reply
msmtp: could not send mail (account amckinley from /home/aden/.msmtprc)