IMAP Authentication Failiure in Sahrepoint 2016 Version


I’m getting

MailKit.Security.AuthenticationException: Authentication failed at MailKit.Net.Imap.ImapClient.Authenticate

in the logs whenever i try and sync mail…i have tried the IMAP settings elsewhere and they are working ok… I’ve read elsewhere this is and issue with MailKit/NTLM and Exchange but obviously I can’t start re-writing your binaries. I’ve also delegated permissions for the Farm account to the mailbox

Love the application and keen to buy but no working with exchange is a deal breaker.


SharePoint not Sahrepoint


extra logging details…

Unexpected Plumsail HelpDesk. Sync timer job error. WebUrl: http://*************/HelpDeskTest. MailKit.Security.AuthenticationException: Authentication failed. at MailKit.Net.Imap.ImapClient.Authenticate(Encoding encoding, ICredentials credentials, CancellationToken cancellationToken) at MailKit.MailService.Authenticate(String userName, String password, CancellationToken cancellationToken) at Plumsail.HelpDesk.Common.Services.Emails.EmailRepository.d__9.MoveNext() at Plumsail.HelpDesk.Common.Services.EmailSyncService.Sync(DateTime startDate, Func`2 cancelationRequestCheck) at Plumsail.HelpDesk.Common.Services.Services.SyncJobService.Sync() at Plumsail.HelpDesk.OnPremises.TimerJobs.SynchronizationTimerJob.‡Ž(Object ) 1d242b9e-4d41-b099-1cfc-3b4ae11a6ce6
11/09/2017 09:20:51.08 w3wp.exe (0x6750) 0x753C SharePoint Foundation User Key ayswq Medium Successfully got user key for user. UserNameSuffix: '0#.w|


Hello @markofsoton,

Thank you for contacting us.

Could you please try to configure Outlook to using the same IMAP settings (the same mail server and the same user account and password) and let us know about the results?

Best regards,
Anna Dorokhova
Plumsail Team


I had this problem and figured it out today. On the incoming mail settings use domain\username for the email address.