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Internal server error

I am currently unable to send any emails. They all bounce back with the following message:
"451 4.3.2 Internal server error"


Receiving emails works as normal. I have phoned my ISP help desk (PlusNet) who have been no help whatsoever. They just say it will probably correct itself eventually!


I can send emails via their webmail without problem but not from Pegasus.


Could anybody advise whether this is actually a Pegasus problem or am I stuck with trying to get PlusNet to sort it please?


I am currently unable to send any emails. They all bounce back with the following message: "451 4.3.2 Internal server error" Receiving emails works as normal. I have phoned my ISP help desk (PlusNet) who have been no help whatsoever. They just say it will probably correct itself eventually! I can send emails via their webmail without problem but not from Pegasus. Could anybody advise whether this is actually a Pegasus problem or am I stuck with trying to get PlusNet to sort it please?
edited Oct 16 at 12:22 pm

Seems is saying an invalid login.


First would do Tools/Internet Options, and check the create log file option at bottom left.
Then Try process again. See what the log file has to show.
Be careful file contains password, so don't upload those lines.


Plusnet SMTP settings are smtp.plus.net or relay.plus.net for the server, with port 587 and STARTTLS encryption recommended. For the username, use your full Plusnet email address, and for the password, use your Plusnet email account password. Some setups may also use port 465 with SSL/TLS or port 25 with None for encryption, so try port 587 first.


Do your setting match that. Note it says full email address versus just the email name.
Which version of Pegasus are you using?


Seems is saying an invalid login. First would do Tools/Internet Options, and check the create log file option at bottom left. Then Try process again. See what the log file has to show. Be careful file contains password, so don't upload those lines. Plusnet SMTP settings are smtp.plus.net or relay.plus.net for the server, with port 587 and STARTTLS encryption recommended. For the username, use your full Plusnet email address, and for the password, use your Plusnet email account password. Some setups may also use port 465 with SSL/TLS or port 25 with None for encryption, so try port 587 first. Do your setting match that. Note it says full email address versus just the email name. Which version of Pegasus are you using?

mikes@guam.net

Using latest Pegasus version 4.91.


My account is with legacy brand so SMTP setting is relay.force9.net.


Port is #25 with no encryption. How do I change this if necessary?


User name and password as suggested.


Done the create log file, where do I find the log please?


By the way this problem has only recently started, Pegasus has been near faultless for a very long time. It did begin before I uploaded latest version though so that can't be the cause.


Using latest Pegasus version 4.91. My account is with legacy brand so SMTP setting is relay.force9.net. Port is #25 with no encryption. How do I change this if necessary? User name and password as suggested. Done the create log file, where do I find the log please? By the way this problem has only recently started, Pegasus has been near faultless for a very long time. It did begin before I uploaded latest version though so that can't be the cause.
edited Oct 16 at 5:46 pm

First. From my experience with Port 25.
At one point, it was available as an open port, but then hackers abused it.
So, many ISP's started blocking access from outside there domain IP addresses.
With my local ISP, I can use Port 25 on my home network, since it is in that domain.
Later, the encrypted option with special ports came out. This works from outside ISP domain.
So, probable best to setup with the encrypted port.


The log file is a subdirectory under your mail directory.
TCPlogs
The files will have extension for the pop and smtp transaction.
Might give more info on exact error.


Under Pegasus.
Tools/Internet Options / SMTP settings.
Then edit your settings.
Click security.
Never would be if you are allowed port 25 access.
Second option is probable what you need, but it varies between ISP?


The SMTP authentication is dependent on ISP.
I use the 2nd one and login with my userid and password.
My ISP just uses name with out domain


At somepoint I had used the first one, but my ISP at one point had the pop3 and smtp on same server, and now they are different ones.


Might have to just try differnt options.


But would look at log file first.
Again. If you upload parts of log file, make sure to delete lines that mention password.


First. From my experience with Port 25. At one point, it was available as an open port, but then hackers abused it. So, many ISP's started blocking access from outside there domain IP addresses. With my local ISP, I can use Port 25 on my home network, since it is in that domain. Later, the encrypted option with special ports came out. This works from outside ISP domain. So, probable best to setup with the encrypted port. The log file is a subdirectory under your mail directory. TCPlogs The files will have extension for the pop and smtp transaction. Might give more info on exact error. Under Pegasus. Tools/Internet Options / SMTP settings. Then edit your settings. Click security. Never would be if you are allowed port 25 access. Second option is probable what you need, but it varies between ISP? The SMTP authentication is dependent on ISP. I use the 2nd one and login with my userid and password. My ISP just uses name with out domain At somepoint I had used the first one, but my ISP at one point had the pop3 and smtp on same server, and now they are different ones. Might have to just try differnt options. But would look at log file first. Again. If you upload parts of log file, make sure to delete lines that mention password.

mikes@guam.net

My account is with legacy brand so SMTP setting is relay.force9.net.
From directions I found at https://www.plus.net/help/email-guides/how-to-set-up-plusnet-email/ you should use:


  1. Incoming server: mail.force9.net
  2. Incoming port: 995
  3. Security: STARTTLS
  4. Outgoing server: relay.force9.net
  5. Outgoing port: 587 (recommended)
  6. Security: STARTTLS

I stopped using ports 25 (SMTP) and 110 (POP3) quite awhile ago in favor of 587 and 995 (SSL/STLS). I'm surprised it's still being used.


BTW, it's a must you share your session log to pin-point the error cause. Remember to mask login/password data before posting.


[quote="pid:58130, uid:36008"]My account is with legacy brand so SMTP setting is relay.force9.net.[/quote]From directions I found at https://www.plus.net/help/email-guides/how-to-set-up-plusnet-email/ you should use: 1. Incoming server: mail.force9.net 2. Incoming port: 995 3. Security: STARTTLS 4. Outgoing server: relay.force9.net 5. Outgoing port: 587 (recommended) 6. Security: STARTTLS I stopped using ports 25 (SMTP) and 110 (POP3) quite awhile ago in favor of 587 and 995 (SSL/STLS). I'm surprised it's still being used. BTW, it's a must you share your session log to pin-point the error cause. Remember to mask login/password data before posting.

-- Euler

Pegasus Mail 4.91.1746 Windows 7 Ultimate
IERenderer: 2.7.3.2 AttachMenu: 1.0.2.0
PMDebug: 2.5.8.37 BearHTML 4.9.9.6

edited Oct 16 at 7:56 pm

This is the sent log, user name and password removed:


13:41:10.627: --- 17 Oct 2025, 13:41:10.627 ---
13:41:10.627: Connect to 'mail.force9.net', timeout 15 seconds, flags 16842753.
13:41:11.672: >> +OK POP3 ready 1340286763.1760704869@mail.enmail.co<cr><lf>
13:41:11.672: << USER <cr><lf>
13:41:11.688: >> +OK<cr><lf>
13:41:11.688: << <cr><lf>
13:41:11.879: >> +OK logged in.<cr><lf>
13:41:11.879: << STAT<cr><lf>
13:41:11.898: >> +OK 0 0<cr><lf>
13:41:11.911: << QUIT<cr><lf>
13:41:11.943: >> +OK Bye-bye.<cr><lf>
13:41:11.953: --- Connection closed at 17 Oct 2025, 13:41:11.953. ---
13:41:11.953:


This is the returned error log, email addresses removed:
13:41:12.672: --- 17 Oct 2025, 13:41:12.672 ---
13:41:12.678: Connect to 'relay.force9.net', timeout 15 seconds, flags 16842753.
13:41:13.703: >> 220 mail.enmail.co ESMTP ready<cr><lf>
13:41:13.703: << EHLO [192.168.1.164]<cr><lf>
13:41:13.813: >> 250-mail.enmail.co<cr><lf>
13:41:13.813: >> 250-AUTH PLAIN LOGIN<cr><lf>
13:41:13.813: >> 250 STARTTLS<cr><lf>
13:41:13.829: << MAIL FROM:<><cr><lf>
13:41:13.909: >> 250 2.0.0 OK<cr><lf>
13:41:13.909: << RCPT TO:<><cr><lf>
13:41:14.019: >> 451 4.3.2 Internal server error<cr><lf>
13:41:14.030: << QUIT<cr><lf>
13:41:14.035: >>
13:41:14.035: --- Connection closed at 17 Oct 2025, 13:41:14.035. ---
13:41:14.035:


This is the sent log, user name and password removed: 13:41:10.627: --- 17 Oct 2025, 13:41:10.627 --- 13:41:10.627: Connect to &#039;mail.force9.net&#039;, timeout 15 seconds, flags 16842753. 13:41:11.672: &gt;&gt; +OK POP3 ready &lt;1340286763.1760704869@mail.enmail.co&gt;&lt;cr&gt;&lt;lf&gt; 13:41:11.672: &lt;&lt; USER &lt;cr&gt;&lt;lf&gt; 13:41:11.688: &gt;&gt; +OK&lt;cr&gt;&lt;lf&gt; 13:41:11.688: &lt;&lt; &lt;cr&gt;&lt;lf&gt; 13:41:11.879: &gt;&gt; +OK logged in.&lt;cr&gt;&lt;lf&gt; 13:41:11.879: &lt;&lt; STAT&lt;cr&gt;&lt;lf&gt; 13:41:11.898: &gt;&gt; +OK 0 0&lt;cr&gt;&lt;lf&gt; 13:41:11.911: &lt;&lt; QUIT&lt;cr&gt;&lt;lf&gt; 13:41:11.943: &gt;&gt; +OK Bye-bye.&lt;cr&gt;&lt;lf&gt; 13:41:11.953: --- Connection closed at 17 Oct 2025, 13:41:11.953. --- 13:41:11.953: This is the returned error log, email addresses removed: 13:41:12.672: --- 17 Oct 2025, 13:41:12.672 --- 13:41:12.678: Connect to &#039;relay.force9.net&#039;, timeout 15 seconds, flags 16842753. 13:41:13.703: &gt;&gt; 220 mail.enmail.co ESMTP ready&lt;cr&gt;&lt;lf&gt; 13:41:13.703: &lt;&lt; EHLO [192.168.1.164]&lt;cr&gt;&lt;lf&gt; 13:41:13.813: &gt;&gt; 250-mail.enmail.co&lt;cr&gt;&lt;lf&gt; 13:41:13.813: &gt;&gt; 250-AUTH PLAIN LOGIN&lt;cr&gt;&lt;lf&gt; 13:41:13.813: &gt;&gt; 250 STARTTLS&lt;cr&gt;&lt;lf&gt; 13:41:13.829: &lt;&lt; MAIL FROM:&lt;&gt;&lt;cr&gt;&lt;lf&gt; 13:41:13.909: &gt;&gt; 250 2.0.0 OK&lt;cr&gt;&lt;lf&gt; 13:41:13.909: &lt;&lt; RCPT TO:&lt;&gt;&lt;cr&gt;&lt;lf&gt; 13:41:14.019: &gt;&gt; 451 4.3.2 Internal server error&lt;cr&gt;&lt;lf&gt; 13:41:14.030: &lt;&lt; QUIT&lt;cr&gt;&lt;lf&gt; 13:41:14.035: &gt;&gt; 13:41:14.035: --- Connection closed at 17 Oct 2025, 13:41:14.035. --- 13:41:14.035:

13:41:14.019: >> 451 4.3.2 Internal server error<cr><lf>
Below text excerpts from the Web:



SMTP Email Error 451 4.3.2 occurs when an email server is experiencing temporary failure. It may indicate that the server is experiencing a massive system overload, or is simply undergoing maintenance.



Server Overload, Maintenance and Updates, and Resource Constraints are what they call "temporary issues" that should be gone already. I believe you are experiencing none of these. OTOH, this may explain your problem:



Anti-Spam Measures - Email servers often implement dynamic security measures to temporarily limit the number of incoming connections. This is to monitor any suspicious activity, especially from those that are receiving or sending a large number of emails.
Although blocks from Anti-Spam measures are mostly categorized under SMTP Error 471, there is still a chance for some senders to receive an email error code 451 4.3.2 due to this circumstance.



You reported using port 25 to SMTP access and this might be the case here...



Port 25 SMTP connections are typically unencrypted. Moreover, by default, port 25 doesn’t require connecting parties to authenticate. This leads to a vulnerable SMTP service configuration known as an open relay, which allows any application to send email to that service without restrictions. A mail server intentionally or accidentally configured as an open relay will forward emails from any sender to any recipient, regardless of where those emails originated.
Due to these security deficiencies, port 25 is often exploited by spammers, scammers and other cybercriminals who use it distribute spam emails, phishing emails and malware. To mitigate this risk, many Internet Service Providers (ISPs) and cloud hosting providers often block port 25. Unfortunately, these countermeasures can sometimes negatively impact email deliverability.



So, what I think is that your mail provider is doing (or trying to) is blocking port 25 usage. The fact you're using STARTTLS (starts as unencrypted connection and may or may not switch to encrypted) entails a question: Are you still using SMTP port 25 instead of port 587?


[quote=&quot;pid:58133, uid:36008&quot;]13:41:14.019: &gt;&gt; 451 4.3.2 Internal server error&lt;cr&gt;&lt;lf&gt;[/quote]Below text excerpts from the Web: &gt; SMTP Email Error 451 4.3.2 occurs when an email server is experiencing temporary failure. It may indicate that the server is experiencing a massive system overload, or is simply undergoing maintenance. Server Overload, Maintenance and Updates, and Resource Constraints are what they call &quot;temporary issues&quot; that should be gone already. I believe you are experiencing none of these. OTOH, this may explain your problem: &gt; Anti-Spam Measures - Email servers often implement dynamic security measures to temporarily limit the number of incoming connections. This is to monitor any suspicious activity, especially from those that are receiving or sending a large number of emails. Although blocks from Anti-Spam measures are mostly categorized under SMTP Error 471, there is still a chance for some senders to receive an email error code 451 4.3.2 due to this circumstance. You reported using port 25 to SMTP access and this might be the case here... &gt; Port 25 SMTP connections are typically unencrypted. Moreover, by default, port 25 doesn&rsquo;t require connecting parties to authenticate. This leads to a vulnerable SMTP service configuration known as an open relay, which allows any application to send email to that service without restrictions. A mail server intentionally or accidentally configured as an open relay will forward emails from any sender to any recipient, regardless of where those emails originated. Due to these security deficiencies, port 25 is often exploited by spammers, scammers and other cybercriminals who use it distribute spam emails, phishing emails and malware. To mitigate this risk, many Internet Service Providers (ISPs) and cloud hosting providers often block port 25. Unfortunately, these countermeasures can sometimes negatively impact email deliverability. So, what I think is that your mail provider is doing (or trying to) is blocking port 25 usage. The fact you&#039;re using STARTTLS (starts as unencrypted connection and may or may not switch to encrypted) entails a question: Are you still using SMTP port 25 instead of port 587?

-- Euler

Pegasus Mail 4.91.1746 Windows 7 Ultimate
IERenderer: 2.7.3.2 AttachMenu: 1.0.2.0
PMDebug: 2.5.8.37 BearHTML 4.9.9.6

"Are you still using SMTP port 25 instead of port 587?"


Yes. It has been like that since 1998, I have never changed anything since initial set up, screen grabs below. What do I need to change and how?


68f2594a16747
68f2594908ceb


&quot;Are you still using SMTP port 25 instead of port 587?&quot; Yes. It has been like that since 1998, I have never changed anything since initial set up, screen grabs below. What do I need to change and how? ![68f2594a16747](serve/attachment&amp;path=68f2594a16747) ![68f2594908ceb](serve/attachment&amp;path=68f2594908ceb)
edited Oct 17 at 3:59 pm

Brian, you'll need to make a couple easy changes. I'm using your images to show it:
68f282268e08d
68f282269a511


The SMTP authentication is important. It's the same login/password you already use to download messages via POP3. Pegasus make it easy for you as you don't have to type it again, just inform host's name used for POP3 access of the mail account.


Brian, you&#039;ll need to make a couple easy changes. I&#039;m using your images to show it: ![68f282268e08d](serve/attachment&amp;path=68f282268e08d) ![68f282269a511](serve/attachment&amp;path=68f282269a511) The SMTP authentication is important. It&#039;s the same login/password you already use to download messages via POP3. Pegasus make it easy for you as you don&#039;t have to type it again, just inform host&#039;s name used for POP3 access of the mail account.

-- Euler

Pegasus Mail 4.91.1746 Windows 7 Ultimate
IERenderer: 2.7.3.2 AttachMenu: 1.0.2.0
PMDebug: 2.5.8.37 BearHTML 4.9.9.6

The SMTP authentication is important. It's the same login/password you already use to download messages via POP3. Pegasus make it easy for you as you don't have to type it again, just inform host's name used for POP3 access of the mail account.

Aside from this, switching to StartTLS or SSL connect will prompt you for changing the port automatically, you just need to verify the proper port number.


[quote=&quot;pid:58136, uid:2194&quot;]The SMTP authentication is important. It&#039;s the same login/password you already use to download messages via POP3. Pegasus make it easy for you as you don&#039;t have to type it again, just inform host&#039;s name used for POP3 access of the mail account.[/quote] Aside from this, switching to _StartTLS_ or _SSL connect_ will prompt you for changing the port automatically, you just need to verify the proper port number.
			Michael
--
IERenderer's Homepage
PGP Key ID (RSA 2048): 0xC45D831B
S/MIME Fingerprint: 94C6B471 0C623088 A5B27701 742B8666 3B7E657C
edited Oct 17 at 9:58 pm

All done and seems to have fixed the problem. Many thanks for your help gentlemen, much appreciated.


All done and seems to have fixed the problem. Many thanks for your help gentlemen, much appreciated.
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