Suppose the server has a maximum bandwidth of 100Mbps. Suppose there are 5 new emails on the server, each containing an attachment, the size of the emails is the date for example, almost the size of the attachment, with very little text. January 5: 130KB January 4: 120KB January 3: 110KB January 2: 100KB January 1: 15MB Assuming that Outlook starts receiving from the earliest date, i.e. January 1, January 2... At this time, Outlook receives messages very fast, almost reaching the server's maximum bandwidth of 100Mbps. However, if the size of the e-mail is like this. January 5: 15MB January 4: 100KB January 3: 110KB January 2: 120KB January 1: 130KB Outlook reception is very slow, about 10Mbps or slower, almost 10 times slower, even 20 times slower. In other words. When the first message received by Outlook is large, it is very fast from the first to the last message, just like the rate at which the first attachment is downloaded, which is very fast. When Outlook receives a small message, it is very slow from the first to the last message. I've tested it over and over again, but I still don't know what's causing it. The server also hosts a web site, through the browser repeatedly tried to download a single file (500MB or more) from the site at different times, no matter when, the speed is very fast. Has anyone else experienced this problem? Thank you!
Trying to measure the speed for receiving single emails in Mbps as you did does not make much sense to me. Email is a text-based protocol where messages between the mail client and server are exchanged similar to talking to a human (search the web for manually testing a mail server with telnet if you want to learn a bit more about that). This explains why small messages must be way slower that downloading a big chunk of data. Plus, mail servers are handling many clients simultaneously, so measuring speed in the way you did will give you no indication on how powerful your mail server is. That said, there is neither anything wrong with the behaviour of your mail system nor is it slow nor does the whole test like this makes sense as nobody would expect that a mail system will fill a 100Mbit connection with a small message between one Outlook system and a postfix server.
I understand what you're saying, but it seems that's not what I'm trying to say. What I was trying to say was. When the first email has a large attachment, the total time to receive 5 emails is about 1 minute. When the first email has a small attachment, the total time to receive 5 emails is about 15 minutes. Besides, it's in beta, and I'm the only user. I'm sorry!
Okay, that's completely different to your irst question, especially as it's not related to any speed measured in Mbps. Check your system's mail.log to see if you get any errors, like timeouts or so. Also, this might not be system speed related at all, it just might be that your test email is watched by greylisting and the sending server waited 15 minutes to retry delivery.
I checked the system mail.log, and there are no errors or timeouts or any other abnormalities. Also, before I opened Outlook, I logged into Webmail to confirm that 5 emails existed and that there was nothing unusual on the surface, and I even opened Outlook to receive them at least 12 hours after Webmail had confirmed them. Also, like you, I don't even think it has anything to do with system speed, but after repeated attempts, it does appear to be what I'm talking about, so I don't know what's going on.
What are the timestamps in mail log? Check on sending sided and receiving side, at what time do the messages get sent and arrive at destination. Also, use command mailq to see if messages are waiting in mailqueue.
It might be a good idea to just test it in some other mail client like thunderbird aswell to see if the issue is outlook itself or something else
As I said before, I confirmed receipt of 5 e-mails at Webmail, 12 hours before I opened Outlook to receive them. Also, there is no queue.
I'm still testing this scenario, because this situation is not absolute, and my tests are only useful if this situation occurs.
Have you examined the received e-mails, showing full headers? There should be "Received:" -lines with timestamps, they should show at what phase of the delivery there is long delay.
I don't think this has anything to do with the mail delivery itself. It seems like an issue with his MUA in this case Outlook as the mails are directly visible in Roundcube but only hours later in Outlook
maybe (probably completely) wrong, but is it possible outlook is set to some different timezone to the pc it's running on and isn't displaying emails that it's already received because it thinks the receiving time is still somewhere in the future? it's the sort of unexpected and completely stupid behaviour i'd expect from something like outlook.
I'm sorry! Maybe I didn't describe the problem clearly because I'm not a native English speaker. Roundcube and Outlook are almost synchronized as far as visibility is concerned, there is no gap of a few hours. As soon as there is a new message on the server, it is immediately visible in Roundcube and received in Outlook. The hours I originally mentioned, 12 hours, just happened to be in the middle of the night and I needed to rest, so I started the test the next day, which was 12 hours apart.
Thanks to all of you, the problem has been solved. This is due to some network delays across the region.
