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Strange email behaviour

Posted: Wed Jan 18, 2017 11:08 am
by ercatli
My wife and I both use one of our Exetel email accounts on two separate computers. We have set the account so it deletes downloaded messages after a week, to make sure both of us get to see all incoming emails.

But about 24 hours ago, the account started to behave strangely. For quite a few hours I could see the incoming emails on my computer but she could not. Then, for no apparent reason, a whole bunch of emails from the last few hours downloaded to her Inbox. Then it stopped for another few hours for her while still being fine for me, then again the outstanding emails downloaded. Currently it isn't receiving again on her computer, still OK on mine.

We both use Mac Mail and we haven't changed anything lately that I'm aware of. The account settings on both computers seem to be the same.

Can anyone help me know how I might debug this please? Is there some setting I can check? Has Exetel changed anything regarding email accounts (I doubt it)?


Re: Strange email behaviour

Posted: Wed Jan 18, 2017 1:09 pm
by ercatli
Just one further comment. I'm starting to see what may be a pattern here. It seems like my wife's computer receives download emails into her Inbox about once every 4-6 hours. Is that possible?

Re: Strange email behaviour

Posted: Wed Jan 18, 2017 4:31 pm
by Dazzled
POP email servers have a very simple interface, that accepts a small number of commands in plain text. There's a list at Your computer mail client, no matter how the GUI display is constructed, sends these requests. Normally sent are user name, password, a list of waiting messages by ID number, retrieve message by number, and delete message from the server.

It really is simple and goes back to early days when we typed everything at a terminal. Graphic screens were unheard of. Modern email client software can build up email lists, both on the server and stored in your computer, and display them in various ways. They have timers to check the server at fixed intervals. (The time comes from the operating system). Your timers appear to be involved.

Your two Macs have software that add functionality, and that's where the trouble will lie.

If you have telnet you can still do email on the terminal on both your computers and see how it operates, or check that the server is indeed working.

Is this useful?

Re: Strange email behaviour

Posted: Thu Jan 19, 2017 2:49 pm
by ercatli
Thanks. The problem seems to have righted itself again. I'm not sure if I know how to use the info you've given me to debug, but if the problem occurs again I will try. Thanks.

Re: Strange email behaviour

Posted: Thu Jan 19, 2017 4:37 pm
by Dazzled
If you wish to give the terminal a try to confirm everything works the old-fashioned way, it's pretty simple, like this (you type the italicised):
$ telnet 110
Connected to
Escape character is '^]'.
+OK Dovecot ready. (Here there be dragons!)
PASS yourpassword
+OK Logged in.
+OK 3 messages:
1 2182
2 2182
3 2191
+OK 2182 octets
.........,plain text message number 1 follows.......
+OK Logging out.

Don't be scared by the dragons. DELE <number> will delete from the server. Retrieve the message first! This is all your software is doing underneath the screen display, at whatever time intervals are configured.

The message comes in in its true text format including headers, which the GUI clients usually strip off. Test with plain text emails, as HTML formatted ones will come back in HTML, which the client has to interpret.

Re: Strange email behaviour

Posted: Thu Jan 19, 2017 4:58 pm
by ercatli
OK, that's a lot clearer thanks. I'll give it a go.