Outlook.com emails not sending from em Client

I noticed that emails were staying in the Outbox and not being sent yesterday afternoon. I have deleted my outlook.com account in em Client and recreated it but the problem persists.

In the em Client log I see the following:

[SMTP] MailClient.Accounts.AuthenticationAbortedException: Authentication aborted
at MailClient.Protocols.Smtp.SmtpSendCommand.Authenticate(WorkerStatus status)
at MailClient.Protocols.Smtp.SmtpSendCommand.Connect(WorkerStatus status)
at MailClient.Protocols.Smtp.SmtpSendCommand.Execute(WorkerStatus status)
at MailClient.Commands.Command.Process(WorkerStatus status)…

I have checked my Microsoft account and em Client has been granted the appropriate permissions.
Is anyone else experiencing this issue?

With the loss of outlook email connectivity back in October and now this, I’m starting to lose faith in em Client.

lunes 07 diciembre 2021 :: 1249hrs (UTC +01:00)

Hi @Vel

I do not use Outlook, however, two things…

1./ Yes, I have noticed that there have been several people with a similar issue over the past few days
2./ The October outage was an acknowledged Microsoft issue that they eventually corrected and not eMC
I am sorry I cannot help you, I suggest you raise a ticket with eMC

¡Saludos desde la soleada Sevilla en España!


Hablo español, luego portugués e inglés, con conocimiento de varios otros idiomas.

Stesso tuo problema… o risolvono a breve oppure disdico tutto

I have tried the following steps to resolve this issue:

Changed the SMTP port from 587 to 25 and 465 with the respective SSL/TLS settings.
Disabled my anti virus.
Installed em Client on a macbook - same issue persists.
Rebooted my router.
Changed from my router to a 4G hotspot for connectivity, to further rule out the router.

None of the above allowed me to send emails from an outlook.com account.

I installed Thunderbird to see if it would expereince the same issue. It did not and was able to send emails from the same outlook.com account.

I compared the Thunderbird SMTP settings to EMC and noticed that Thunderbird uses smtp.office365.com instead of smtp-mail.outlook.com used by EMC. I changed this in EMC and still got the same result - the authentication aborted issue persists.

Given I have tried a W10 PC, a Macbook, different network connectivity and different ports with EMC without success but Thunderbird works perfectly on the same account, I can only assume that something is amiss with the EMC outlook.com connectivity for my outlook account.

I should add that I have also tested with a Gmail account and EMC works perfectly.

When the Microsoft outage that was resolved, I had to remove and re-add my Outlook account (via the automatic wizard) in eM Client and that then worked fine for me. Try removing and re-adding your acct.

Before removing and re-adding your account, backup first via “Menu / Backup”.

(Outlook SMTP settings)

Hi @cyberzork

Thank you for the suggestion. I had already tried that but decided to try again. This time I also used the Microsoft account page to revoke all access for EMC (deleting an account from EMC does not do that) so that it really was a “fresh” creation of the outlook account in EMC.

Unfortunately the result was the same. The SMTP authentication still aborts according to the EMC log and emails cannot be sent but remain in the Outbox.

A Quick Update

I have no idea what has changed but as of 5mins ago, EMC suddenly started sending emails again!

Great you email is now sending ok. Sounds like some sort of (external smtp issue) that is resolved.

This time I also used the Microsoft account page to revoke all access for EMC (deleting an account from EMC does not do that)

eM Client cannot automatically remove (eM Client program access) from your Microsoft account when you remove and account due to “Privacy” reasons. Only the owner can do that manually.

Yes, I am aware of that hence the reason I mentioned it. It is the 1 step that was missing from completely “divorcing” the existing outlook account from EMC and is probably a step worth taking to ensure that the authorisation mechanism is completely refreshed.

It seems that perhaps Microsoft may have been “tweaking” things again, with unexpected consequences. :wink: