I'm having a small problem with my mail server and I hope somebody will have an idea or two.
My mail server runs FreeBSD 7.1 with a fully updated port system. I use Postfix as an MTA requiring SASL to send via SMTP and has TLS support to encrypt messages. I use amavisd-new and clamav to scan e-mail as it arrives. (No spam filter, just viruses.) I also use postgrey to implement greylisting. The mail server is on it's own dedicated 3.0 meg down/512k up DSL line. There are three network cards in the server - one goes to the DSL modem, another via cat5 to a laptop in my office for administration, and another to a wireless router. Customers can connect to the wifi router (AKA hotspot) and use our internet on ports 80 and 8080; pf simply passes the data on these ports out the DSL line and blocks all other connections from that network interface. Our business has a separate 6.0 meg down/768k up DSL line. The mail client is Mozilla Thunderbird.
The problem is that when somebody sends an e-mail with a large attachment (~3-8 meg), sometimes it will send and other times not. The bigger the attachment, the more likely sending is to fail. Here's the kicker - if I send mail using the administration laptop in my office connected directly to the server or using a computer connected to the wifi hotspot (also local to the server, though it has to be looping through the NICs because pf does not allow SMTP from the wifi card), messages can be sent with large attachments without a problem. To me, this indicates a problem with the DSL line connecting the server to the internet. However, tests run by my ISP show the line to be fine and there are no drops shown in /var/log/messages or /var/log/ppp.log, just the normal automatic re-authentication via PPPoE after 20 hours of being connected.
I just did a test and reproduced the trouble. Thunderbird was sending fine and stalled at 51%, then said that sending of message failed because connecting to the SMTP server failed. Looking on the server, there's nothing new in /var/log/messages or /var/log/ppp.log, and /var/log/maillog indicates simply 'postfix/smtpd[pid]: lost connection after DATA (nnnn bytes) from unknown[ip]' followed by 'disconnect from unknown[ip]'.
I'm frankly at a loss of what to do next. Any ideas of what might be wrong or what to try to troubleshoot further?
My mail server runs FreeBSD 7.1 with a fully updated port system. I use Postfix as an MTA requiring SASL to send via SMTP and has TLS support to encrypt messages. I use amavisd-new and clamav to scan e-mail as it arrives. (No spam filter, just viruses.) I also use postgrey to implement greylisting. The mail server is on it's own dedicated 3.0 meg down/512k up DSL line. There are three network cards in the server - one goes to the DSL modem, another via cat5 to a laptop in my office for administration, and another to a wireless router. Customers can connect to the wifi router (AKA hotspot) and use our internet on ports 80 and 8080; pf simply passes the data on these ports out the DSL line and blocks all other connections from that network interface. Our business has a separate 6.0 meg down/768k up DSL line. The mail client is Mozilla Thunderbird.
The problem is that when somebody sends an e-mail with a large attachment (~3-8 meg), sometimes it will send and other times not. The bigger the attachment, the more likely sending is to fail. Here's the kicker - if I send mail using the administration laptop in my office connected directly to the server or using a computer connected to the wifi hotspot (also local to the server, though it has to be looping through the NICs because pf does not allow SMTP from the wifi card), messages can be sent with large attachments without a problem. To me, this indicates a problem with the DSL line connecting the server to the internet. However, tests run by my ISP show the line to be fine and there are no drops shown in /var/log/messages or /var/log/ppp.log, just the normal automatic re-authentication via PPPoE after 20 hours of being connected.
I just did a test and reproduced the trouble. Thunderbird was sending fine and stalled at 51%, then said that sending of message failed because connecting to the SMTP server failed. Looking on the server, there's nothing new in /var/log/messages or /var/log/ppp.log, and /var/log/maillog indicates simply 'postfix/smtpd[pid]: lost connection after DATA (nnnn bytes) from unknown[ip]' followed by 'disconnect from unknown[ip]'.
I'm frankly at a loss of what to do next. Any ideas of what might be wrong or what to try to troubleshoot further?