smtp timeouts

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networkn

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Topic # 68442 21-Sep-2010 23:09

Hi There!

Since moving our systems to Vodafone Internet (The only thing that changed), we have started to get smtp 420 tcp errors on our logs for our mail server to ISP's like xtra, and gmail for some reason. It was suggested we try adjusting the MTU, which was 1492, but we subsequently changed to 1500, due to web browsing issues. This fixed all the email problems for a day, now we only have issues with some people rather than everyone.

What is the correct setting and why would I be getting 420 TCP errors?

BlakJak

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Reply # 382948 21-Sep-2010 23:37

For starters, you shouldn't be screwing with your MTU; the defaults are good in almost all cases. Of course the caveat to this is, what sort of internet access is it? DSL?

Can you quote an exact error message and the circumstances around when you get it?

You're running a mailserver, what platform is it? Do you do your own MX lookups or do you relay through your ISP? Do you have a static IP address?

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networkn

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Reply # 382950 21-Sep-2010 23:46

VFNZ suggested changing it because we couldn't even surf properly when they first connected it. We run Groupwise (latest version and SP, but none of that has changed since we had no issues, the ONLY change was a move to VF). It's a DSL Connection and we get the error send email when the ISP is XTRA, almost always, but also other ISP's randomly such as Orcon (Was almost everyone before we changed the MTU).

The error message is Response: 420 TCP write error

BlakJak

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Reply # 382955 22-Sep-2010 00:13

Interesting, only heard of the need to reduce MTU on PPPoE connections.

Sounds like you're doing direct SMTP. Can you configure groupwise to send all outgoing email to the Vodafone SMTP server instead, see what happens?

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networkn

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Reply # 382957 22-Sep-2010 00:16

Hi There!

I had it configured to do that and the problem was worse.

I think there is something wrong with my connection. today I was getting 11/.75 on my connection via speedtest, right now I am getting 2/.40.

I am thinking I have made a horrible mistake moving to VF!

BlakJak

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Reply # 382959 22-Sep-2010 00:18

Perhaps you should talk to their helpdesk before making too many assumptions. That's what they're there for, after all...

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networkn

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Reply # 383311 22-Sep-2010 19:22

Ok well I think I have a better understanding of some of the details now.

It seems like frequently the first time communication occurs it times out.

If I requeue the messages, the second time they go. If I click web links that frequently don't work the first time, they immediately go. If I initate a RDP connection, the first time it times out and the second works perfectly.

What could cause that?