SMTP Protocol Returned a Transient Error

HCL Domino Domino Forum
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I have an issue trying to send email to one domain. Everytime I try I get the above message returned. My Setup is as follows:

mail.wire-e.co.uk on Domino6 running on Red Hat Linux 7.3. This is my main mail server and sends all mail. It is linked up to a 2Mb Lease Line.

mail2.wire-e.co.uk on Domino6 running on Windows 2000 Server. This is my back up mail server and only receives mail. It is linked up to a 1Mb ADSL line.

mail and mail2 replicate with each other to transfer mail and update mail boxes.

Reverse lookups on both MX records are resolved.

However, if I swap my gateway on my main mail server over to the ADSL line, I can send email to this domain.

As far as I know my set up is not an open relay.

I now do not know where the problem lies. Is it with a) my ISP, b) my Server Config or c) the domain I am trying to send to.

Can anyone help me at all please. It would be greatly appreciated.

Kind regards,

Adrian

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Subject: SMTP Protocol Returned a Transient Error

Adrian, I have just had exectly the same problem sending to Tiscali in the UK. I first tried to send a email which had attachments of just over 2Mb. Suspecting they had some filtering which stopped such a message size, I broke the email into five for the five files, the first went fine, the rest have so far been stopped with the same error. I am not sure but it may be something we are going to see more and more as ISP try blocking spam.Can any one else throw some light on this?

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Subject: RE: SMTP Protocol Returned a Transient Error

This was the reply from my ISP

"Hiya,

I suspected that this may be that the 2Mb line had no reverse DNS

and barclays require this to send them mail. However, this is not

the case. In fact, both IP’s have forward and reverse entries;

227.194.240.212.IN-ADDR.ARPA domain name pointer mail.wire-e.co.uk

mail.wire-e.co.uk has address 212.240.194.227

141.235.103.212.IN-ADDR.ARPA domain name pointer

adsl-235-141.as15758.net

adsl-235-141.as15758.net has address 212.103.235.141

From the router however I have tried to connect to the mail servers

listed in DNS for them and I get the following;

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

demon-gw#telnet 213.120.81.204 25

Trying 213.120.81.204, 25 … Open

421 4.0.0 mailgate02.barclays.co.uk Server error

[Connection to 213.120.81.204 closed by foreign host]

demon-gw#telnet 62.189.96.212 25

Trying 62.189.96.212, 25 … Open

421 4.0.0 mailgate01.barclays.co.uk Server error

[Connection to 62.189.96.212 closed by foreign host]

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

From here, and from a few test connections I can connect to

both of these IP’s ok. I have also tried to connect to

these machines from an IP in the same /24 subnet you

are using, and this also works ok.

This looks like they are not accepting mail from you/your

IP’s for some reason. I am not sure what policies they use,

but as mentioned above it does not appear DNS related.

Do they have an IT/support address you are able to contact

[via the 1Mb line] to find out why they are dropping connections

from your IP’s?

If they can check their server logs, it dropped my connection

attempts at 12:27 to both IP’s.

As this appears to be something from their side, i dont think

I can fix the issue. Please let me know if there is anything

further I can do.

I hope this helps"

Looks like the company I am trying to send to is being over cautious.

Don’t know if this will help someone else.

4

Subject: RE: SMTP Protocol Returned a Transient Error

Did you ever get to the bottom of why this was happening? Was it in fact on their side? Funny, but I am having the issues with the same servers, mailgate01 + 02.barclays.co.uk. They are dropping my server connection.

Thanks,

Mark