Indy SMTP blocked as SPAM by ISP

Giganews Newsgroups
Subject: Indy SMTP blocked as SPAM by ISP
Posted by:  Chris (chr…
Date: Tue, 28 Jun 2005

Using Indy 9.0. and wrote a small app that tries to deliver text messages to
fleet of trucks. Unfortunately some of the drivers are using Verizon and
some are using SPRINT PCS phone numbers. SPRINT PCS works fine but with
Verizon I am being rejected with a:

Remote host said: 550 SMTP connection refused.

from the Verizon ISP or text message address xxxxxxxx… where
xxxxxxxxxx is the phone number.

Have tested single message using Outlook and everything works fine with
Verizon just to verify that I am sending to correct address.  Wild guess
here is that Verizon considers me a SPAMMER unless I use Outlook instead of
Indy.  Have seen some Knowledge Base articles that suggested removing the
X-Library Header TAG, and some that say you should use POP3 Retrieval First
and then SMTP with Authenticate(). But to no avail..  Is there another work
around or is this resolved with Indy 10.0?

Somewhat of a Indy novice and apologize if I am in the wrong forum and any
help would be appreciated.