Using stunnel to Get Alerts via GMail - Still Blocked

[zoroastr]

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GIVING UP (maybe)
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OK, I think I'm finally giving up on this. After banging on the problem intermittently for several days, the closest I get is this:
Following alledm's suggestion in the thread https://www.zabbix.com/forum/showthread.php?t=21509, I'm using stunnel as a client for the Gmail server. Everything is in place, but I keep getting these in zabbix-server.log when it tries to send out.

25834:20140202:094910.509 wrong answer on MAIL FROM [530 5.5.1 http://support.google.com/mail/bin/answer.py?answer=14257 rb6sm12515114pbb.41 - gsmtp

.
...and my host's journal returns logs like these for every attempt:

Feb 02 10:12:40 my-hostname stunnel[20696]: LOG5[20696:140380102063872]: Service [ssmtp] accepted connection from 127.0.0.1:43271
Feb 02 10:12:40 my-hostname stunnel[20696]: LOG5[20696:140380102063872]: connect_blocking: connected 74.125.129.109:465
Feb 02 10:12:40 my-hostname stunnel[20696]: LOG5[20696:140380102063872]: Service [ssmtp] connected remote server from 192.168.1.102:49134
Feb 02 10:12:40 my-hostname stunnel[20696]: LOG5[20696:140380102063872]: Connection closed: 61 byte(s) sent to SSL, 235 byte(s) sent to socket
Feb 02 10:13:10 my-hostname stunnel[20696]: LOG5[20696:140380102063872]: Service [ssmtp] accepted connection from 127.0.0.1:43287
Feb 02 10:13:10 my-hostname stunnel[20696]: LOG3[20696:140380102063872]: connect_blocking: connect 2607:f8b0:400e:c02::6d:465: Network is unreachable (101)
Feb 02 10:13:10 my-hostname stunnel[20696]: LOG5[20696:140380102063872]: connect_blocking: connected 74.125.129.108:465
Feb 02 10:13:10 my-hostname stunnel[20696]: LOG5[20696:140380102063872]: Service [ssmtp] connected remote server from 192.168.1.102:46364
Feb 02 10:13:10 my-hostname stunnel[20696]: LOG5[20696:140380102063872]: Connection closed: 63 byte(s) sent to SSL, 235 byte(s) sent to socket

So, it seems that my Zabbix-internal configs for Email Meida Type, Action, etc., are all OK; I'm just not getting the notification because Google's not happy with the inputs it's getting. At least, that's twhat the logs seem to be saying.

Here are some particulars of the current config. If any gurus out there can spot something obviously wrong, that would be great. SSMTP works well; I can send myself test mails from the command prompt all day long (gets a little boring, tho)...

Email Media Type:
Name: Email
Type: Email
SMTP server: localhost
SMTP helo: localhost*
SMTP Email: [email protected]
enabled

* ...for the 'helo' line, I've tried localhost ip, actual hostname, fqdn, etc

...stunnel.conf:

; My client mode Services

[gmail-pop3]
client = yes
accept = 127.0.0.1:110
connect = pop.gmail.com:995

[ssmtp]
client = yes
accept = localhost:25
connect = smtp.gmail.com:465

[nntp]
client = yes
accept = localhost:119
connect = ssl-us.astraweb.com:443

...php.ini - mail function:

; For Unix only.  You may supply arguments as well (default: "sendmail -t -i").
; http://php.net/sendmail-path
sendmail_path = /usr/bin/ssmtp -t

...any suggestions HUGELY appreciated. thx.