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SMTP Mail Delivery Problems

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SMTP Mail Delivery Problems

If anyone from PN is reading this can they please have a look at my customer support ticket no. 20643669 ASAP.

Our email delivery has been diabolical for a couple of weeks now and is impacting our business. I have tried calling customer support today but just get a dead line.

I have done numerous checks at our end to determine that the problem is not with us. I have checked all our hardware and it appears to be OK, I have configured a separate server as an SMTP relay to receive email but that is showing the same symptoms, so I don't believe it is a configuration problem with us. I don't think there is a problem with the line as I have tried using other protocols (such as http) and the performance and throughput is as you'd expect, so it probably isn't a line fault or contention at the exchange.

To recap what is happening: our SMTP mail delivery is extremely slow and has been for a few weeks and it is getting worse and worse. Other SMTP servers can connect to ours but then the transfer rate appears to be so slow that they cannot deliver mail before the connection times out.

The autoturn queue currently has over 3800 emails in it and it is increasing all the time. When you issue a 'finger postmaster@autoturn.plus.net' only a few mails get delivered.

When the problem first started things tended to be OK in the morning but gradually got worse throughout the day and then it would tend to recover over night and the autoturn queue would empty then, but now it hasn't emptied for over a week.

What is going on? It's as if the SMTP traffic is being throttled right back to practically nothing. This is really not good enough.

I am really going to have to consider our future as a plusnet customer.

Thank you.
7 REPLIES
Community Veteran
Posts: 26,543
Thanks: 788
Fixes: 9
Registered: 10-04-2007

SMTP Mail Delivery Problems

I've just tried connecting to your smtp server and it appeared extraordinarily slow to respond - even before one tried sending an email to it.

Have you run a speed check on your connection which checks both the up and down speed (e.g. http://www.adslguide.org.uk/tools/speedtest.asp ). Does all other internet activity seem to be at normal speed?

Have you tried rebooting your router and/or server?

Have you checked that your server isn't being used as a spam relay (and hence the connection is being overloaded)?
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
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SMTP Mail Delivery Problems

Yes, I know it's very slow, that's the whole point.

I have ran a speed check and I get about 1500k/200k which is acceptable for a 2MB connection. There was other traffic at the same time so the real speeds would be high than that.

Have rebooted many times.

The server is not being used as a spam relay, and we only use this connection for mail so there is no other network traffic using all the bandwidth.
Community Veteran
Posts: 26,543
Thanks: 788
Fixes: 9
Registered: 10-04-2007

SMTP Mail Delivery Problems

Was that speed test run on the server or from another PC?
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
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SMTP Mail Delivery Problems

I have run the speed test from both the server and another connected machine using one of our other static IP's with similar results.
Community Veteran
Posts: 26,543
Thanks: 788
Fixes: 9
Registered: 10-04-2007

SMTP Mail Delivery Problems

If it wasn't for the fact that you've set up a different server, I'd suggest that what you've said pointed to a problem at your end. Have you got all ports forwarded to the server or just port 25 - is it providing any other services (e.g. http or ftp)?

Is the number of simultaneous inbound connections limited in any way? (I wonder if it's spending more time deciding what to do than doing!)
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
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SMTP Mail Delivery Problems

All ports are forwarded to the server as the router doesn't have any firewalling abilities. The firewall is Microsoft ISA server which is on the same machine as the exchange/smtp server. As it's only used for mail delivery the only ports open are those needed for smtp, pop3, imap etc.

I don't believe the problem is to do with traffic at our end as quite often you'll see umpteen smtp server connections but the traffic led's on the router show practically no traffic what so ever, i.e. they flash intermittently every couple of seconds rather than continuously.
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SMTP Mail Delivery Problems

Things appear to be moving now. Have PN done anything?

One thing I know that's changed is the IP address I'm delivering to. When I set up the second server earlier I put it on a different IP address but as I had to wait for plusnet to update their DNS records I couldn't test it, so I temporarily swapped the IP addresses around so the mail would go to the new server but it made no difference.

Now the DNS records appear to have updated as some mail is coming through the new IP address and servers connecting to both my smtp servers are having no problems delivering mail. The autoturn queue has already dropped by almost a 1000.

I will leave this run like this for now and put everything back on the original IP address tomorrow and see what happens.

As a side issue, the finger command to trigger the autoturn queue only works on the original IP address not the second one, is there a reason for this?

Cheers

Gary