[[ paq@iota ~ ]] echo 49 | swaks --server 10.0.76.255:11125 --attach-name 49.txt --attach - --from billy@microsoft.com --to stallman@gnu.org --header 'Subject: Hello!' --body 'Hello, my friend! How are you?'
=== Trying 10.0.76.255:11125...
=== Connected to 10.0.76.255.
<-  220 xxx-mail-bcc-54f7bc5ffb-77vbp Python SMTP 1.1
 -> EHLO localhost
<-  250-xxx-mail-bcc-54f7bc5ffb-77vbp
<-  250-SIZE 33554432
<-  250-8BITMIME
<-  250-STARTTLS
<-  250 HELP
 -> MAIL FROM:<billy@microsoft.com>
<-  250 OK
 -> RCPT TO:<stallman@gnu.org>
<-  250 OK
 -> DATA
<-  354 End data with <CR><LF>.<CR><LF>
 -> Date: Thu, 05 Apr 2018 19:15:12 +0300
 -> To: stallman@gnu.org
 -> From: billy@microsoft.com
 -> Subject: Hello!
 -> X-Mailer: swaks v20130209.0 jetmore.org/john/code/swaks/
 -> MIME-Version: 1.0
 -> Content-Type: multipart/mixed; boundary="----=_MIME_BOUNDARY_000_14470"
 ->
 -> ------=_MIME_BOUNDARY_000_14470
 -> Content-Type: text/plain
 ->
 -> Hello, my friend! How are you?
 -> ------=_MIME_BOUNDARY_000_14470
 -> Content-Type: application/octet-stream; name="49.txt"
 -> Content-Description: 49.txt
 -> Content-Disposition: attachment; filename="49.txt"
 -> Content-Transfer-Encoding: BASE64
 ->
 -> NDkK
 ->
 -> ------=_MIME_BOUNDARY_000_14470--
 ->
 ->
 -> .
<-  250 OK
 -> QUIT
<-  221 Bye
=== Connection closed with remote host.