When accessing Gmail via IMAP access by using any email client including iPhone, Apple Mail, Thunderbird and Outlook, the following error message may appear, requesting user to manually input the user name and password again in order to authenticate with Google’s Gmail or GoogleMail IMAP server again.

Your IMAP server wishes to alert you to the following: Invalid credentials (Failure)

Your IMAP server wishes to alert you to the following: Invalid credentials (Failure)

The error looks like a Gmail mechanism to protect against robots or automated scripts, and probably to stop and halt abnormal bandwidth utilization (upload and download) or abusing account activity such as using Gmail as storage space drive or transferring other mail account to Gmail.

Another reason for the invalid credentials or web login requires error to happen is too frequent mail checking. Gmail Help recommends to set mail client to check for new messages not more than once every 10 minutes.

If you’re very sure that you’re using a correct password and username (with @gmail.com after the user name), and not checking email in Gmail’s Inbox too frequently, you may need to clear and unlock the CAPTCHA. To unlock CAPTCHA for Gmail account, go to the following URL:


Note: For Google Apps user, visit https://www.google.com/a/yourdomain.com/UnlockCaptcha instead, with yourdomain.com as the valid domain name.

Type in the email address, password for the Gmail address, and fill in the correct Captcha validation. Click on “Unlock” button to fix the IMAP failure error.

For user who still faces the problem after clear the Captcha can try to use an alternative IMAP server instead, which is imap.googlemail.com on SSL port 993.

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  • Stephen Roper

    FYI My Outlook client required that I “Allow less Secure Apps” this is a security setting with in gmail.

  • Benita Kowal

    Istill can not receive mail

  • Ian

    Doesn’t work.

  • Chris

    Outstanding … fixes SPB Wallet syncronization setup “Invalid credentials when syncing via google acct (gmail)”

  • geoffm

    man, this was such a pain! thanks for the info, I’ll tell all my friends about this.

  • cheddar

    Leaving this comment here in case anybody ever finds it useful… If you are using this from a shell, and your password has a shell expansion character in it, be sure to treat it literally.

    E.g. if your password is a$df and you are using bash, make sure you enter it into the command line as ‘a$df’.

  • Stan Bush

    Worked for me.. thanks

  • cristopher

    I try to do the captcha but when a press unlock my password it´s not recognized i have an accounts in google app and no one of my partners can resolve this problema because our passwords not works

  • joe

    Thanks you very much for sharing this. Saved me time indeed,


  • Cecilia

    Thank you so much! I was struggling with it for an hour till I run into this post!

  • Tin

    Thank you so much

  • CrazyD

    It works EXCELLENT!

    Thank you! You just saved me hours of frustration.

    Date: 14.07.2011

  • Om Deshmukh

    Gr8 Help…. Captcha thing worked for me…. Thanks a LOT……

  • cyclone


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  • Totor55

    Great help, Thanks!

  • Kasungee

    This is really very useful. Thanks a lot. Keep it up..

  • Woori

    Thanks so much. It's very helpful to me.

  • bae

    No luck despite all the above.

    My gmail IMAP times out from all client now, webmail ok.

    I have been using on Mac Mail + iPad + Android for months

    Have tried unlock captcha + new password + disable/enable IMAP + POP3 alternative in all combinations

    All clients disabled before trying with just one, still no luck

    Any advice anybody????

  • Roger

    Very helpful, thanks for your post.

  • Bradley

    Thank you so much for taking the time to publish this! We've been trying to set up an iPhone with Gmail (but Google Apps mail) for hours with no luck. My only thought was that it was that I had just switched IMAP settings to "on" and I was just going to wait it out. Thanks again!

  • Eric

    Marvelous. Thank you for publishing this. I've been knocking my against the wall for two hours fiddling with my Thunderbird IMAP server settings.

  • Manoj

    Thanks for the info. Unlocked CAPTCHA and the thunderbird started working.. I assume that mine was due to over checking. I have thunderbird IMAP checking gmail in parallel on two computers, 1 iphone and web-browsers..

  • john

    Thankyo kind sir. Sorted now.

  • Paris

    It works! Thanks for sharing.

  • Martin

    I tried all the above, the thing that worked for me was as simple as changing the password, even though the old password would let me into the webmail.

    Once I changed the password on gmail webmail, and changed it in outlook afterwards, it worked immediately.

  • Adam

    Hi there,

    the same problem as Romain – I've returned home and I found that my Thunderbird client shows error with Invalid Credentials. Well, I tried (three times) insert a password, but still error. Then I used CAPTCHA, but still nothink happens. I tried the password again – not a difference.

    Can you help me how to solve this?

    Thanks a lot.

  • Tomas

    I find the solution!.

    Found a solution.
    For my case, I used the client OutlookExpress 6, setting up an account with IMAP. Gmail's instructions do not explain that you specify in the account settings, both email addresses.
    Must be entered explicitly in "My server requires password".


  • Amy Jo Yates

    Perfect fix for me! Glad I found you.

  • Claribel

    Hey. Do you accept guest bloggers? How do I submit a post?

  • owat

    It works! Thanks for sharing.


  • Romain


    (sorry for my english)

    It's dont works!

    The impa is active in my gmail account

    i've unlock the captcha

    I'v try with imap.googlemail.com

    But i've the message : invalid Credentials (Failure)

    Do you have any solution?

    thanks you

  • dude

    DUDE!! I love you so much man you definitely saved me, I was really starting to PANIC, none of my google services were working on my palm pre. Now I'm back in business thanks to you. THANKS!

  • Palo

    It was really very useful. Thanks a lot.

  • Kaps

    Hi Dude

    It is really useful. I faced many problems due to this while connecting to google apps frm my code.

    Thanks a lot. Keep sharing such hidden inforamation :-)

  • New iPhone User

    Thanks so much! My IMAP problem was driving me nuts until I came across the unlock the CAPTCHA fix. Thanks you!!

  • Dimitri

    Thanks! This driving me nuts on my palm pre, and now it works fine.

    Thanks alot!

  • AP

    Thank you so much for sharing this important info!

  • Robert


  • Krishna

    Well, I did have that problem for Invalid Credidentials, till I realized I had the wrong password, put the right one in, theng got the web login error, unlocked the captcha, worked, THANKS!

  • rachel

    thank you so so much for the help! i was on the phone for hours with apple and att and no one had a clue how to fix it. thank you!

  • Tacito

    Thanks a lot!!! Great hint!

  • Akshay

    thanks dude.. it was amazing help… thanks a ton

  • Thomas

    Thank you very much for this tip/tutorial.Fixed my imap problem on my Palm Pre. Great site.

  • Andreas

    Thank you so very much, now I can use my SE-phone to post to WordPress.

  • H

    Thanks for the tip much appreciated

  • K Goode

    That did the trick, thank you for saving me from any more frustration.

  • JD

    Thanks mate; been trying to get my gmail working with Alpine on Linux for days after it suddenly stop working, luckly I stumbbled accross your blog post.

    Search tags:

    'alpine gmail web login required', 'alpine gmail can't login'

  • chandra

    Great. Thanks problem solved

  • brian

    you are awesome, saved the day!

  • Wow, this was a life saver! Thanks :)

  • Amit Agarwal

    Thanks a lot. I just didnt know about this Captcha. My settings seemed fine and yet I was unable to configure gmail correctly on my SE T700.

    But now it works perfectly.


  • M.

    Thank you! You just saved me hours of frustration.

  • Brandon Phelps

    Do you know if you pay for a subscription if google still limits the checking to every 10 minutes?


  • We're using Google Apps for our company email and I was trying in vain to connect to the IMAP server with Microsoft Entourage 2008 for Mac, constantly seeing the 'Web login required' failure message.

    But the unlock Captcha method seems to have resolved the issue. I don't understand that whole technical explanation, but hey. It works now.


  • Thanks for the simple instructions. It worked great.

  • my imap is working now!

    thanks a lot.

  • Shawn Gillespie

    I did the above and it is only a temp fix. I was having to do it everyday. Yesterday I must have unlocked the CAPTCHA 20 times.

    So I went back and looked at Gmail's recommended IMAP client settings at http://mail.google.com/support/bin/answer.py?hl=e

    So it's been 48 hours and no errors.

    NB: Pay special attention to the section at the bottom with general rules.

  • help me

    very very helpful. thanks a lot.

  • Anonymous

    Thanks for the help!