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Microsoft Hotmail : "Outgoing server (SMTP) timed out"

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I am using Thunderbird v 115.5.1 on a Windows 10 system. I am using an "@hotmail.com" email address. I seem to be able to receive emails just fine, but face an issue sending out emails. When I press "send", it gets stuck on "sending message" for quite a while, then I see the error message:

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Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) smtp.office365.com timed out. Try again.

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My SMTP settings: Server Name: smtp.office365.com Port: 587 Connection Security: STARTTLS Authentication Method: OAuth2

Appreciate any help! :)

I am using Thunderbird v 115.5.1 on a Windows 10 system. I am using an "@hotmail.com" email address. I seem to be able to receive emails just fine, but face an issue sending out emails. When I press "send", it gets stuck on "sending message" for quite a while, then I see the error message: ===== Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) smtp.office365.com timed out. Try again. ===== My SMTP settings: Server Name: smtp.office365.com Port: 587 Connection Security: STARTTLS Authentication Method: OAuth2 Appreciate any help! :)

All Replies (9)

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Hello there We have read the messsge We try to help

The common message for sending an email with an attachment that is downloaded is too large to process, for example for the mail server service.

Whether this service takes too long for this action.

This is not able to process this and you will receive the above-mentioned message on your screen, just like yours.


Greetings Firefox volunteer

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Hello there


To start with, you can indeed check whether the outgoing Smtp configuration is okay.

try to send all data to a backup file first so that your data is safe before you start

After that contact me.

we could run and find a solution together to set the time out server.

Greetings Firefox volunteer.

Modified by Googlethunderbird

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Your settings are correct. What's the antivirus? They often cause timeouts if allowed to scan outgoing mail. If you have an app that isn't Windows Security, it's more likely to cause issues.

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sfhowes said

Your settings are correct. What's the antivirus? They often cause timeouts if allowed to scan outgoing mail. If you have an app that isn't Windows Security, it's more likely to cause issues.

Thanks for this suggestion :) I have AVG Antivirus installed. I didn't suspect this to be the cause because I have 2 email accounts set-up on Thunderbird, an @hotmail.com one as well as an @gmail.com one. I have never had an issue sending out emails from the gmail one.

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googlethunderbird said

Hello there We have read the messsge We try to help The common message for sending an email with an attachment that is downloaded is too large to process, for example for the mail server service. Whether this service takes too long for this action. This is not able to process this and you will receive the above-mentioned message on your screen, just like yours. Greetings Firefox volunteer

Sorry, but I really cannot understand what you're trying to tell me...

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kevinlim said

sfhowes said

Your settings are correct. What's the antivirus? They often cause timeouts if allowed to scan outgoing mail. If you have an app that isn't Windows Security, it's more likely to cause issues.

Thanks for this suggestion :) I have AVG Antivirus installed. I didn't suspect this to be the cause because I have 2 email accounts set-up on Thunderbird, an @hotmail.com one as well as an @gmail.com one. I have never had an issue sending out emails from the gmail one.

It's generally recommended to disable AV scanning of the profile folder and also of secure connections. With AVG/Avast, this means disabling the Email or Mail Shield.

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Hello there

Sending files that are too large appears to be impossible.

you can set up your server if disabling your security didn't help.

The server time out settings can be changed to give your request a longer time to download your email files than normal.

Add ons can also be a part of the cause.


Greetings Firefox volunteer.

Modified by Googlethunderbird

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Hello there

To do this, you bypass the specified time for the server download that is specified by default in your software and then you essentially bypass the error you are experiencing.

It’s called setting the time out for the server.


Greetings Firefox volunteer

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Hello there

I hope you were able to find your solutions with the answers of our information.


Greetings Firefox volunteer