it's their server that is rejecting you and if they actually know what they are doing they should be able to tell you exactly why.  All we can do is guess but they should actually be able to give you a firm answer other than thunderbird works and pegasus doesn't therefor it is a pegasus problem.  Also saying webmail works therefore there is no problem makes no sense at all sense they are 2 completely different things.

Greetings All,

I have been using Pegasus since the early 1990's with out any major problems. Yesterday I tried to send a message and got a delivery failure notice. I checked all my internet settings and all are correct. I even uninstalled Pegasus and reinstalled and still no luck. I went and downloaded Thunderbird and tried with it and was able to send with no problem. Here is a copy of the failure notice I received on a test message which has the same 554 message as on all the other failure notices:

Delivery has failed on the enclosed message for the following
reasons reported either by the mail delivery system on the mail
relay host or by the local TCP/IP transport module:

   554 Service unavailable; Client host [67-218-79-134.dyn.actaccess.net] blocked using Barracuda Reputation; http://www.barracudanetworks.

Your original mail message follows:
--------------------------------------------------------

X-PM-Identity: <Default>
From: hmscook@rangeweb.net
To: hmscook@rangeweb.net
Date: Mon, 16 Apr 2012 12:11:09 -0600
MIME-Version: 1.0
Subject: test
Message-ID: <4F8C60BD.15107.18055D@hmscook.rangeweb.net>
Priority: normal
X-mailer: Pegasus Mail for Windows (4.63)
Content-type: text/plain; charset=US-ASCII
Content-transfer-encoding: 7BIT
Content-description: Mail message body

TEST
 

 I have also done a virus scan on all the files on the computer. Any ideas? I sure do not want to give up one of my favorite programs of all time.

Cheers,

 Timothy Cook

> I have been using Pegasus since the early 1990's with out any major
> problems. Yesterday I tried to send a message and got a delivery
> failure notice. I checked all my internet settings and all are
> correct. I even uninstalled Pegasus and reinstalled and still no luck.
> I went and downloaded Thunderbird and tried with it and was able to
> send with no problem. Here is a copy of the failure notice I received
> on a test message which has the same 554 message as on all the other
> failure notices:

> Delivery has failed on the enclosed message for the following
> reasons reported either by the mail delivery system on the mail
> relay host or by the local TCP/IP transport module:
>
>    554 Service unavailable; Client host [67-218-79-134.dyn.actaccess.net]
> blocked using Barracuda Reputation; http://www.barracudanetworks.
 

Nothing wrong with the sending but it looks like the receiving system is blocking the Pegasus Mail host being used to send the mail.  Can't tell for sure since the URL is not complete on this message so I can't get a full explanation.

Greetings Thomas,

 I sent all that there was for the URL. So am I gathering that you think that my ISP is blocking Pegasus mail? The message I sent was a test message to my self. I also sent one to my Yahoo address and got the exact same failure message back. What other information would you need to help identify the problem?

 Cheers,

Timothy

>  I sent all that there was for the URL. So am I gathering that you
> think that my ISP is blocking Pegasus mail?

Nope, the way I see this is that the receiving server is blocking mail from the IP address/host name of the sending system, that is what the bounce message says to me.

> The message I sent was a test message to my self. I also sent one to
> my Yahoo address and got the exact same failure message back. What
> other information would you need to help identify the problem?

I assume that you are using the same server for sending both messages so I am guessing the server you are using is running Barracuda and it's doing the rejection.

You need to ask the people running the server as to why you are getting rejected as a spammer.  I guess it is possible that the people setting up the Barracuda anti-spam can be rejecting on the header line in the body of the message identifying Pegasus Mail but that is not the error message.

Greetings Thomas,

Just got off the phone with my ISP tech support and they are certain the problem is with Pegasus. Their reasoning is that since I can send with Thunderbird and with webmail that there is no problem with their servers. So I do not know what to do as I really do not want to give up on Pegasus. Any suggestions?

Cheers,

Timothy

I read the error message to mean quite literally that they are blocking you based on the host name of your ip.  

I would check to make sure you are using a password when sending email

tools | internet options | Sending(SMTP)  tab |  Edit | Security tab

check the box "Login to the SMTP server using the following details"

and put in your username and password

> Just got off the phone with my ISP tech support and they are certain
> the problem is with Pegasus. Their reasoning is that since I can send
> with Thunderbird and with webmail that there is no problem with their
> servers. So I do not know what to do as I really do not want to give
> up on Pegasus. Any suggestions?

It's their Barracuda system that is doing the rejection, Pegasus  Mail is doing nothing wrong.

Turn on session logging and go back to the ISP with a copy of the session log and ask them why this session is being rejected.  You will probably have to send them a copy of the session log as well but since they are rejecting you then that may be a problem.