Why doesn't telnet + relay.plus.net get to gmail?

[#1]

I'm having trouble sending email to my gmail account using telnet + relay.plus.net.

I've tried over several days, and always get something like 250 CpfP1t0063Hd7nU01pfz9t mail accepted for delivery.  The mail never arrives though.  I've also tried it to my yahoo account and that doesn't arrive either.  Clearly the relay is working, at least it's receiving my input.

Is there a problem with the relay, or is it something to do with google anti spam stuff?  Before you ask, yes I looked in my spam folder   Also, I do need to use a telnet mechanism so posh clients are out...

[#2]

It would help to know exactly what commands you're typing into the telnet session?

I'm guessing you're omitting certain headers that makes the email look spammy and causes Gmail/Yahoo to drop the message.

[#3]

telnet relay.plus.net 25
Trying 212.159.8.107...
Connected to relay.plus.net.
Escape character is '^]'.
220 avasout04 smtp relay.plus.net
ehlo relay
250-avasout04 hello [80.229.167.152], pleased to meet you
250-HELP
250-AUTH LOGIN PLAIN
250-SIZE 104857600
250-PIPELINING
250-8BITMIME
250 OK
mail from:cossoft@cossoft.plus.com
250 <cossoft@cossoft.plus.com> sender ok
rcpt to:address@gmail.com
250 <address@gmail.com> recipient ok
data
354 enter mail, end with "." on a line by itself
test from me to me!
.
250 Cz4B1t0033Hd7nU01z4dQi mail accepted for delivery
quit
221 avasout04 smtp closing connection
Connection closed by foreign host.

address@gmail.com has been changed to protect the ignorant 

Run a few minutes ago, and still no sign of yesterday's tests.  What headers could I add?  I don't need any authorisation as I'm "one of the family".  I've not read anything on this forum regarding additional headers...

[#4]

I also sent this to mailinator.com:

telnet relay.plus.net 25
Trying 212.159.8.107...
Connected to relay.plus.net.
Escape character is '^]'.
220 avasout04 smtp relay.plus.net
ehlo relay
250-avasout04 hello [80.229.167.152], pleased to meet you
250-HELP
250-AUTH LOGIN PLAIN
250-SIZE 104857600
250-PIPELINING
250-8BITMIME
250 OK
mail from:cossoft@cossoft.plus.com
250 <cossoft@cossoft.plus.com> sender ok
rcpt to:ciril999@mailinator.com
250 <ciril999@mailinator.com> recipient ok
data
354 enter mail, end with "." on a line by itself
test to ciril 999 from me
.
250 CzLL1t0093Hd7nU01zLoU3 mail accepted for delivery
quit
221 avasout04 smtp closing connection
Connection closed by foreign host.

which resulted in getting this @ mailinator:

To:	ciril999
From:	no sender
Message Id:	1467285678-100037050085-ciril999
Subject:	[no subject]
Received:	Thu Jun 30 2016 12:21:18 GMT+0100 (BST)

so the relay is working, but the DATA from the telnet session didn't arrive.  I'm probably doing something wrong, but I thought that my technique was the standard one for telneting to a smtp machine...

[#5]

After the data command the server expects additional header lines where you'd normally supply "from:", "to:" and "subject:" headers, then an empty line to end the headers. Your plain text message follows the empty line with "." on its own ending the message. This is followed by quit to terminate the connection.

As it stands the message lacks those headers and a body. I'm not surprised Google rejects it.

[#6]

I tried this and it was delivered successfully:

~$ telnet relay.plus.net 25
Trying 212.159.9.107...
Connected to relay.plus.net.
Escape character is '^]'.
220 avasout03 smtp relay.plus.net
ehlo relay
250-avasout03 hello [84.93.219.165], pleased to meet you
250-HELP
250-AUTH LOGIN PLAIN
250-SIZE 104857600
250-PIPELINING
250-8BITMIME
250 OK
mail from:<support@plus.net>
250 <support@plus.net> sender ok
rcpt to:<xxxxxxxx@gmail.com>
250 <xxxxxxxx@gmail.com> recipient ok
data
354 enter mail, end with "." on a line by itself
From: support@plus.net
To: xxxxxxxx@gmail.com
Subject: Test message
This is a test message
.
250 D4nk1t0013aiV8c014o9ww mail accepted for delivery
quit
221 avasout03 smtp closing connection

[#7]

Excuse me.  It works.

I made the mistake of using a Microsoft tech note for the smtp commands that didn't mention the TO, FROM and SUBJECT headers.  Duh, but I was thrown by your relay accepting the email with a success message.  I thought that you'd just get an email without a body...

Thanks very much.  So another man plagued by poor technique