Mailbox Lockout

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Joined: Mon Oct 08, 2007 9:56 pm
Location: Victoria, Australia

Mailbox Lockout

Post by aremdee » Mon Dec 10, 2018 5:13 am

This is a little weird. Last week a customer using Outlook 2010 with multiple accounts to their mail server started getting one email address locked out on the server. The logs showed that the connection originated at their office IP address yet the username/password were being flagged "535 Invalid Username or Password", this happened despite resetting the password. I eventually found that their mailbox was actually locked.

I whitelisted their IP address hoping that would fix the issue, yet despite this we still had lock outs happening all morning. The customer finally rebooted all their devices including iPhones etc and the problem cleared up in the afternoon (this was last Friday) so I thought that was the problem, some device on their network was incorrectly authenticating to that mailbox.

The strange thing is this morning I was greeted with an error connecting to one of my email accounts and have been battling this all day. I haven't resorted to resetting my password but when the log shows the "535 Invalid Username or Password" error against my account, unlocking the mailbox on the server allows Outlook (ours is Outlook 2016) to reconnect without problem using the credentials that have been in use for over a month (it's happening now actually). The mailbox is locked and I'm unsure what is triggering this issue. After last Friday I thought I had best update Mailenable to the latest build but this has failed to resolve the problem. By the way this isn't the first time I have had an issue with this mailbox of mine doing this. It's frustrating and I can't for the life of me work out what's going on unless Outlook is garbling the password as it transmits to the server. Another piece of information is that I have probably another 10 email accounts in Outlook connecting to this same server at the same time which are not experiencing this problem.

The IMAP logs show the invalid username and password error as well as the authenticated connections when I unlock the mailbox. Any help will be much appreciated or just some pointers as to where to look to try and solve it.

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Re: Mailbox Lockout

Post by RSN » Sat Feb 09, 2019 9:31 am

Hi Roger,

A little late, but maybe it'll help someone.

I had similar problems with our customers.
We found out that the ME IMAP service has problems with some passwords. If there is a "\" in the password, Outlook cannot log in via IMAP. In the same setup wizard of outlook the SMTP connection is tested successfully.
After changing the password everything works fine.
If you set the password back to the old one it won't work.

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Re: Mailbox Lockout

Post by kiamori » Tue Feb 19, 2019 2:52 am

Restart the service, if this resolves the problem then its a rogue device attempting to many bad connections forcing ME to block your IP address. You can disable this function under SMTP Properties > Security > Connection Dropping, then uncheck the add to denied IP...

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