Elementary error breaks Outlook 2007 POP3 mail, say users

Users are reporting that Outlook 2007 is immensely slow for POP3 email retrieval, because of an elementary error in the way it negotiates with email servers.

Specifically, it sends AUTH as the first command after connection. The server rejects this with an error response. The ensuing time-outs and consequent errors result in much slower mail retrieval, though it does arrive eventually.

I have 8 POP3 accounts that OL 2003 used to query in a minute or two (with 80 spams downloaded). OL 2007 takes 6 minutes. Plus I reckon there are other problems in the UI threading…..

says CW in a comment to an earlier blog post about Outlook 2007 performance. Corroboration comes from user Ken in a comment to this post.

I’ve not yet tested this myself, but will do shortly. It has a kind of horrific plausibility, since everyone at Microsoft uses Exchange for email, not POP3. Therefore POP3 performance will receive much less scrutiny, though you would have thought that the wider beta testing would have picked it up.

I think we will here a lot more about Outlook 2007 performance issues in the coming months, unless Microsoft comes up with a speedy fix for this and other problems.


I’ve run some tests of my own and looked up some RFCs, with a little help from the microsoft.public.outlook.general newsgroup.

I tried Outlook 2007 with two POP3 servers. One is dovecot; the other is also running on Linux though I’m not sure which POP3 daemon it is. With dovecot, my ethernet trace does show a sequence similar to the one the above users are complaining about, something like:

Server: +OK dovecot ready.”

Client: AUTH

Server: -ERR Unsupported authentication mechanism

However, there is no significant delay introduced; it goes right ahead with user and password.

On the other POP3 server AUTH is again sent, but this time does not trigger an error.

There is something that puzzles me though: according to RFC 1734 AUTH should be followed by an authentication mechanism, not left without an argument. And there doesn’t appear to be any need to send AUTH at all in the standard plain setup.

The lack of an argument would explain the error the other users saw:

Server: -ERR An authentication mechanism MUST be entered

May be an email guru can tell me definitively whether Outlook is in the wrong here. However, it strikes me that the problem is only making a minor contribution to the poor performance. Even the timeout of 3 seconds which the user CW refers to is hardly going to make a huge difference.

That said – the fact remains that Outlook 2007 does have performance issues.

16 thoughts on “Elementary error breaks Outlook 2007 POP3 mail, say users”

  1. Yes, it is a big problem. I have had nothing but trouble with Outlook 2007 and POP3. It is unusable on my Vista machine. It has been trying to download ~40 emails (about 1.5Mb in size) for a day now over a very highspeed connection to the Internet.
    I can go to my portable which runs XP and Outlook 2003 and have it retrieve the emails in seconds or use a web interface to review it; however, I just can’t use Outlook 2007 to get my email.

  2. Yes, I have exaxtly the same issue. Outlook 2007 on Vista business is virtually unusable for POP3 accounts. Has anyone found a solution? I guess I will have to reinstall 2003… or Thunderbird…

  3. After some research on the Outlook 2007 problems, I’ve found the following:

    1. The AUTH command is legitimate under RFC 2554 – ftp://ftp.isi.edu/in-notes/rfc2554.txt

    2. AUTH doesn’t slow down the receive at all. See this log segment:

    2007.02.17 11:39:40 POP3 (myserver.com): Port: 995, Secure: SSL, SPA: no
    2007.02.17 11:39:40 POP3 (myserver.com): Finding host
    2007.02.17 11:39:40 POP3 (myserver.com): Connecting to host
    2007.02.17 11:39:40 POP3 (myserver.com): Securing connection
    2007.02.17 11:39:40 POP3 (myserver.com): Connected to host
    2007.02.17 11:39:40 POP3 (myserver.com): +OK Hello there.
    2007.02.17 11:39:40 POP3 (myserver.com): Authorizing to server
    2007.02.17 11:39:40 POP3 (myserver.com): [tx] AUTH
    2007.02.17 11:39:40 POP3 (myserver.com): -ERR Invalid command.
    2007.02.17 11:39:40 POP3 (myserver.com): [tx] USER me@myemailaddress.com
    2007.02.17 11:39:40 POP3 (myserver.com): +OK Password required.
    2007.02.17 11:39:40 POP3 (myserver.com): [tx] PASS *****
    2007.02.17 11:39:40 POP3 (myserver.com): +OK logged in.
    2007.02.17 11:39:40 POP3 (myserver.com): Authorized to host
    2007.02.17 11:39:40 POP3 (myserver.com): Connected to host
    2007.02.17 11:39:40 POP3 (myserver.com): [tx] STAT
    2007.02.17 11:39:40 POP3 (myserver.com): +OK 0 0
    2007.02.17 11:39:40 POP3 (myserver.com): ==== Comparing server and local blobs ====
    2007.02.17 11:39:40 POP3 (myserver.com): ==========================================
    2007.02.17 11:39:40 POP3 (myserver.com): Do deletions: LoS: no
    2007.02.17 11:39:40 POP3 (myserver.com): ========= No blob changes =========
    2007.02.17 11:39:40 POP3 (myserver.com): ===================================
    2007.02.17 11:39:40 POP3 (myserver.com): Disconnecting from host
    2007.02.17 11:39:40 POP3 (myserver.com): [tx] QUIT
    2007.02.17 11:39:40 POP3 (myserver.com): +OK Bye-bye.
    2007.02.17 11:39:40 POP3 (myserver.com): Disconnected from host
    2007.02.17 11:39:40 POP3 (myserver.com): ========= No blob changes =========
    2007.02.17 11:39:40 POP3 (myserver.com): ===================================
    2007.02.17 11:39:40 POP3 (myserver.com): End execution
    2007.02.17 11:39:40 Email Account Name: ReportStatus: RSF_COMPLETED, hr = 0x00000000
    2007.02.17 11:39:40 Email Account Name: Synch operation completed

    The small email is received on a second but it takes Outlook an age to process it!!!

    3. Biggest issue seems to be the way that Outlook uses the PST files! Watch your hard drive light as emails are actually received – the hard drive is getting hammered. This is most noteable when you’ve got large PST files!

    4. Reducing PST files sizes certainly helps with many of the performance issues but how usable is that!!!! I’ve now got multiple PST files set-up with the biggest one of them currently sitting at 500MB. See the recently released KB932086 – http://support.microsoft.com/kb/932086

    5. From trials on my own system, any PST file size about 600MB adversely affects performance. This is a huge backward step! According to Microsoft, the PST filesize must be much larger to affect performance – yeah right!

    6. Even files under 600MB, under certain circumstances, can cause performance issues.


    8. It is amongst other things, a massive issue with the way Outlook 2007 uses PST files.

    Solution, well maybe:
    I’m going to be working with Microsoft PSS on this issue next week. Hopefully they will either come up with a workaround or at least identify there is an issue that needs fixing.

  4. John

    Thanks for your comments

    > 1. The AUTH command is legitimate under RFC 2554

    Except that covers SMTP and this is POP3. However, I believe AUTH is allowable for POP3 as well, but it always has a parameter. So strictly I believe OL 2007 is wrong here.

    Nevertheless, as you note the AUTH issue doesn’t usually slow things up much; that was my conclusion too. Without testing on all the POP3 servers out there it is hard to be sure.

    Let us know how you get on with PSS.


  5. Hi Tim,

    Yeah your right about that being SMTP. It looks to be RFC 1734 that covers POP’s usage of AUTH.


    The RFC does indeed indicate that a parameter should be passed with the AUTH command.

    I’ll probably blog about my experience with MS PSS and will let you know the blog post details.

    Take care and go make a cup of tea while downloading emails with Outlook 2007. Actually, you’ve probably got time to cook a five course dinner and do the washing up! :-).



  6. This is a post I found on technet. This fixes the problem with not being able to receive in Outlook 2007. According to the post, this only works as a fix on Vista though. I am sooo happy I found this post, I’ve been struggling with it for 2 days now!

    Go to Programs/accessories/ and right click on command prompt and select “run as administrator”

    Then type in the following:

    netsh interface tcp set global autotuninglevel=disable

    This worked immediately for me, downloaded 5mb of e-mail in a few seconds (just like the good ‘ol days of Outlook 2003). this is the link to the actual post:


  7. OL 2007 has been brutal with my POP accounts. I’ve gone from having 8 or so accounts down to 3 (with forwarding at the server) to make it remotely usable. OL 2003, no problems.

    Further, every time I actually exit and restart OL 2007, it will RE-DOWNLOAD duplicate POP emails left on the server. As if it is not identifying the unique mail ID and recognizing it’s already pulled it down.

    I am still on XP, so the Vista solution won’t work. I’ll keep digging. No plans to move to Vista now….can’t risk it!

  8. Same problem here. Since I’ve upgraded from OL 2003 to OL 2007 downloading emails from my main Pop3 account is no longer working. I’m using XP, so the Vista fix is no help… This really is a substential problem to quite a number of users, so where is Microsoft’s fix?!?

  9. Thanks guys, I have been trying to resolve this problem for the past three weeks, and after look in about every Microsoft Help site you help me resolve. I am running OL07 in Vista and the instruction gave by Mike on thread 7 resolved my problem. Now it is downloading as supposed. Thanks again.

  10. After weeks of agonisingly watching Outlook ’07 downloading messages on Vista, I took the following steps suggested by Mike Bisson and it works brilliantly. Thanks for all the help. Mike C

    Mike Bisson has posted a comment on Tim Anderson’s blog that offers a fix for Outlook 2007 performance issues when running on Vista:

    Go to Programs -> Accessories and right click on command prompt and select “run as administrator”

    Then type in the following:
    netsh interface tcp set global autotuninglevel=disable

    Absolutely brilliant guys, thanks again

  11. Thank you for this fix! Had an issue with Vista & Outlook 2007 retrieving POP mail; could send SMTP over the default port 25 but port 110 would time out no matter what the setting.

    To reiterate, these instructions did the trick…take note to run the command prompt as ADMINISTRATOR–
    Go to Programs -> Accessories and right click on command prompt and select “run as administrator”

    Then type in the following:
    netsh interface tcp set global autotuninglevel=disable

  12. Hi, does anyone know what to do when Outlook 2007 on Win XP requires to enter POP3 pasword alll the time? Outlook 2003 worked with no issue after upgrade to 2007 it doesnt work. I didnt find solution up to now. Thanks for any idea.

  13. Hi,
    A year ago I bought a new DELL XPS 710, with Vista, and Outlook 2007. From day one I had the typical performance issues with Outlook that everyone complains about. I made the recommended changes to shut off indexing and it cleared up pretty much everything. However about a week or so ago Microsoft blasted down one of there “security” patches, and now Outlook is unusable. Here is what happens:

    1.) I launch Outlook, It comes up shows my folders, then displays the inbox messages, in the Preview pane it displays the latest message.

    2.) Now the fun begins, sometimes thing are slightly different, but most of the time, if it is able to perform its first Send/Receive without locking up, the Preview Pane no longer works, sometimes goes gray, or just doesn’t refresh so whatever window was on top of it remains displayed.

    3.) In addition, to the display failure, Outlook no longer can Send outgoing email, incoming still works. Don’t get that one.

    Has anyone seen this behavior?

  14. Hi,

    Has anyone ever found a fix for the LOOKOUT 2007 Receive issue on XP Pro SP3 POP Accounts?

    I suspect it is the AUTH Command not working on some ISP/Hosting servers and does on others as is my experience but this is way wrong on Microsoft to make users pay for a mistake that worked fine up until LOOKOUT 2007.

    If anyone finds the fix please email me at this address eric-w@carrier-central.com


  15. It seems Microsoft still havent fixed the outlook 2007 POP receiving error on XP (as of Apr 2011). Do they intend to fix the problem they introduced with OL07 or just let everyone suffer with major POP3 mail problems.


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