Ok, well, there's not many places SMTP email can fail silently. 1: your mail server cannot/does not accept the mail. Your email program will display *some* sort of error message.
2: Your mail server cannot/will not forward the message to the MX for the domain in question. You'll almost invariably get a mailer daemon notification about this, though your email program/spam filter/anti virus might do something stupid and hide it from you. 3: The MX for the address cannot/will not accept the message. Again, it will respond with a reason, and your mail server will almost invariably forward that along to you. 4: The recipient's email program cannot/will not get the email from their mail server. And number 4 is likely what's happening here. The email is getting where it needs to go, then getting shunted to somebody's spam folder or something. Mail server logs will tell you exactly what's happening. Telneting to your mail server's submission port (usually 25 or 587) and making with the ESMTP commands might also shed some light. >From memory, and it's been a while since I did direct SMTP support: EHLO <enter> MAIL FROM: [email protected] <enter> RCPT TO: [email protected] <enter> DATA <enter> Hello this is a message. It will look odd in most mail programs, because you're skipping some of the headers that aren't strictly necessary, but most email programs will expect. Still, you'll get back SMTP status codes, as well as a brief description of any problems encountered.<enter> .<enter> quit <enter> -----Original Message----- From: Af [mailto:[email protected]] On Behalf Of Bill Prince via Af Sent: Friday, October 31, 2014 2:38 PM To: [email protected] Subject: Re: [AFMUG] outlook becomes "intermittent" in satellite office I haven't looked at it in person. According to the tech on site, the email "goes out" without error. They've talked to their email provider (Globat), and they've been told that the email gets to the email server (and I don't know if it's exchange or sendmail). Different people in the office use different email clients. Just so happens that the people in the satellite office all use Outlook. I've asked about logs going out of the email server, but they have not had that information yet. bp On 10/31/2014 11:14 AM, Ken Hohhof via Af wrote: > I don't know, my experience with SMTP is, if you don't get an error > message, it went and you need to look at the mailserver logs to see > what happened. Although Outlook is pretty bad about useful error > messages. > > When you say it only occurs with Outlook, I take it you don't mean > that particular email client, but rather it works if you use webmail. > Have you tried temporarily a different email client from the problem > computer, like Thunderbird or Windows Live Mail? > > The most useful thing, especially if you or the customer controls the > mailserver, is to look at the logs right after sending an email. Was > the message received? Was it relayed and did it go to the right > mailserver according to MX records and to the right recipient? Was it > accepted by the recipient's mailserver, and if not, what SMTP error > codes were logged? Is it still in the mailserver queue being retried? > > If you had packet loss so bad that outgoing email didn't work, I'd > expect trouble with incoming mail, webmail, web browsing, etc. > > And if Outlook is unable to send the email, you should get an error > message, and the message should be stuck in the Outlook outbox. > Unless some antivirus program is spoofing to Outlook that it was sent. > > > -----Original Message----- From: Bill Prince via Af > Sent: Friday, October 31, 2014 10:53 AM > To: [email protected] > Subject: Re: [AFMUG] outlook becomes "intermittent" in satellite office > > It was doing this on 5.21; we upgraded to 5.26 as a test. No > difference. And, it's the same router whether it's local (main office) > or remote (satellite office). > > The symptom is that "some" email never reaches the destination only when > sent from a computer in the satellite office, and only when using > outlook. > > If the email is sent from web mail from a computer in the satellite > office, it works fine. Received email is fine. > > Likewise, if the computer is moved from the satellite office to the main > office, it works fine too. > > It's not recipient specific. Sometimes it works, sometimes it doesn't. > Regardless of recipient. > > My current suspicion is that there is "something" going on with the VDSL > link. It's the weakest link in the chain, and using old phone cables > that were buried a couple decades ago. Maybe an MTU issue, but I'm > guessing that it's load related; and SMTP is more sensitive to the issue > than most other things. > > bp > > On 10/31/2014 4:18 AM, Shayne Lebrun via Af wrote: >> Get rid of 5.26; in my experience, it has odd packet loss problems. >> >> Drop down to 5.19, or go up to 6. >> >> Also, what happens to the email that 'doesn't reach it's >> destination?' Are >> you having problems sending, or receiving? >> >> >> -----Original Message----- >> From: Af [mailto:[email protected]] On Behalf Of Bill Prince via Af >> Sent: Thursday, October 30, 2014 8:59 PM >> To: Motorola III >> Subject: [AFMUG] outlook becomes "intermittent" in satellite office >> >> >> This is a bizarre set of symptoms, and I really don't know what is >> going on. >> So I will articulate the facts, and maybe one of you can tell me what >> might >> be wrong. >> >> We have a business subscriber that occupies several buildings. The >> buildings are separated by enough distance that we have to >> interconnect by >> means other than vanilla ethernet. >> >> Our service is delivered to their main office. Our SM is installed >> there >> (PMP450), plus a Mikrotik router on ROS 5.26. The Mikrotik manages 4 >> VLANs; >> 1 business VLAN, which is bridged to the main subnet in the main office. >> The other 3 VLANs are guest VLANs; each on their own >> (private) subnet. >> >> All the computers, etc. work fine in the main office. >> >> The main office is connected to the "guest building" with a VDSL >> modem (~~ >> 800' phone line between buildings). Not much occurs in the guest >> building; >> it has a couple of WiFi APs for the guests. >> >> In the guest building, we've installed an RB260GS switch. It divides >> the >> various ports out to 4 different VLANs. A couple ports are the >> "business >> VLAN", plus 3 different "guest VLANs". The SFP port on the RB260GS >> is used >> to connect to the "satellite office" another couple hundred yards >> beyond the >> guest building. The SFP port is on the business VLAN. >> >> At the satellite office, they have 2 computers. Everything on the 2 >> computers in the satellite office seems to work just fine. Web >> browsing, >> streaming youtube, etc. >> >> However, when they run Outlook, "some" email doesn't go to the >> destination. >> As far as we can tell, it gets to their off-site SMTP server >> (Globat), but >> some of it doesn't ever reach its destination. If they use their >> web-based >> email, the email works every time. Also, the POP part of the email works >> just like you'd expect. >> >> Today, we moved one of the computers back to the main office, and >> surprise, >> surprise, Outlook starts working just like it's supposed to. >> >> We've run extended ping tests between the satellite office and the main >> office, and there is no break in the link. It seems solid. So >> where/how is >> the SMTP part of email breaking? >> >> What tests can I run to figure this out? >> >> >> -- >> bp >> >> > > >
