re :The main identity works well but email sent from the second identity is received in the gmail account as from the main identity.

So you have not created two mail accounts, one for each, but have one mail account with an additional identity using a different email address.

As you say: I have configured the second identity with a name and the same email address which I have as an alias in Outlook, leaving the other options as default (because they are ok for me).

As the other options remain as default, you are sending using the main identity Outgoing Server SMTP server which is using the main identity email address and password.

As the email was actually sent and received in gmail account, this tells me that the second alias email address used in 'FROM' is allowed to be received by Outgoing server, but it seems as if it does not send to the gmail account using that alias. As if the Outlook.com has a different setting to use a specific default when sending and is ignoring the 'FROM'

Your IMAp Sent folder shows: 2 saved emails for each test with the second identity: one which says it is from the main identity and another wich says it is from the second identity.

Please check in the main email address webmail account via browser and confirm that you can receive and send your alias email address via the main address account. It sounds like Outlook is configured to receive various alias, but uses the main one to send it on. Sounds mad to me, but this could be Outlook themselves.

Look at this info: http://www.howto-outlook.com/faq/aliases.htm

TRy: Create another Outgoing Server (SMTP) for the alias email address and then in the alias email address, Settings tab, select to use that specific Outgoing Server.

Toad-Hall said

Please check in the main email address webmail account via browser and confirm that you can receive and send your alias email address via the main address account.

I can send and receive email to and from both email addresses/aliases from Outlook web client. (I have been doing that for a lot of time).

I also receive email from both aliases in my IMAP folder in Thunderbird (I do not need to configure the second identity for this).

Toad-Hall said

Look at this info: http://www.howto-outlook.com/faq/aliases.htm

I have already seen that 'faq' link and now another time and the only clue is to configure another account for the alias. I have tried to configure the second alias as an account in Thunderbird: I receive the email ok, but when I send mail from that account, I get the same behavior as with the second identity; The email is received as it was sent from the main alias and two emails saved on sent IMAP folder.

Toad-Hall said

TRy: Create another Outgoing Server (SMTP) for the alias email address and then in the alias email address, Settings tab, select to use that specific Outgoing Server.

Is it possible to do this in Thunderbird? I have not found the way.

By the way, it seems it may be an issue related to SMTP and Outlook with aliases in general and not only with Thunderbird, so I will also check it also with Microsoft/Outlook guys.

re :Create another Outgoing Server (SMTP)

In Thunderbird Tools > Account Settings > Outgoing Server (SMTP) or right click on mail account in Folder pane and select 'Settings'

then select 'Outgoing Server (SMTP)' in the left pane. Click on 'Add' Enter details for the alias email address and the outgoing server name. click on OK

click on 'Manage Identites' buttons select the alias identity On Settings tab Outgoing Server - select the one you just created. click on all OK's.

I have tried creating another Outgoing Server (SMTP) for the secondary alias with the same result.

I have also tried with the latest version on Windows 10 with the same result.

I got in contact with Microsoft support but, knowing that the web client works, they do not care about third party tools.

Looking for more information I came across logging, so I have enabled it for SMTP. At the end is the result on Linux: just open Thunderbird, send an email with the secondary alias and close. I have changed the email accounts to a description for privacy.

On windows, the log file was pretty the same, but:

Windows logging main difference

SMTP Send: MAIL FROM:<secondaryalias@outlook.com> .

Linux logging file

1610909568[7f555ed17580]: SMTP Connecting to: smtp-mail.outlook.com 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 220 BLU436-SMTP151.smtp.hotmail.com Microsoft ESMTP MAIL Service, Version: 8.0.9200.16384 ready at Thu, 20 Aug 2015 13:59:24 -0700 1610909568[7f555ed17580]: SMTP entering state: 14 1610909568[7f555ed17580]: SMTP Send: EHLO [192.168.1.4] 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-BLU436-SMTP151.smtp.hotmail.com Hello [95.121.146.75] 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-TURN 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-SIZE 41943040 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-ETRN 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-PIPELINING 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-DSN 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-ENHANCEDSTATUSCODES 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-8bitmime 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-BINARYMIME 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-CHUNKING 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-VRFY 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-TLS 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-STARTTLS 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250 OK 1610909568[7f555ed17580]: SMTP entering state: 4 1610909568[7f555ed17580]: SMTP entering state: 21 1610909568[7f555ed17580]: SMTP Send: STARTTLS 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 220 2.0.0 SMTP server ready 1610909568[7f555ed17580]: SMTP entering state: 19 1610909568[7f555ed17580]: SMTP entering state: 14 1610909568[7f555ed17580]: SMTP Send: EHLO [192.168.1.4] 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-BLU436-SMTP151.smtp.hotmail.com Hello [95.121.146.75] 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-TURN 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-SIZE 41943040 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-ETRN 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-PIPELINING 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-DSN 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-ENHANCEDSTATUSCODES 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-8bitmime 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-BINARYMIME 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-CHUNKING 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-VRFY 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250-AUTH LOGIN PLAIN XOAUTH2 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250 OK 1610909568[7f555ed17580]: SMTP entering state: 4 1610909568[7f555ed17580]: SMTP entering state: 21 1610909568[7f555ed17580]: SMTP entering state: 16 1610909568[7f555ed17580]: Logging suppressed for this command (it probably contained authentication information) 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 235 2.7.0 Authentication succeeded 1610909568[7f555ed17580]: SMTP entering state: 18 1610909568[7f555ed17580]: SMTP entering state: 3 1610909568[7f555ed17580]: SMTP Send: MAIL FROM:<mainalias@outlook.com> SIZE=448 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250 2.1.0 mainalias@outlook.com....Sender OK 1610909568[7f555ed17580]: SMTP entering state: 5 1610909568[7f555ed17580]: SMTP Send: RCPT TO:<destinationemail@gmail.com> 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250 2.1.5 destinationemail@gmail.com 1610909568[7f555ed17580]: SMTP entering state: 6 1610909568[7f555ed17580]: SMTP Send: DATA 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 354 Start mail input; end with <CRLF>.<CRLF> 1610909568[7f555ed17580]: SMTP entering state: 7 1610909568[7f555ed17580]: SMTP entering state: 8 1610909568[7f555ed17580]: SMTP Send: . 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 250 2.6.0 <55D63FAC.3080705@outlook.com> Queued mail for delivery 1610909568[7f555ed17580]: SMTP entering state: 9 1610909568[7f555ed17580]: SMTP Send: QUIT 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP entering state: 0 1610909568[7f555ed17580]: SMTP Response: 221 2.0.0 BLU436-SMTP151.smtp.hotmail.com Service closing transmission channel 1610909568[7f555ed17580]: SMTP entering state: 10 1610909568[7f555ed17580]: SMTP entering state: 12 1610909568[7f555ed17580]: SMTP connection error quitting 804b0002, ignoring

Outlook Identities DO NOT WORK WITH MAIL CLIENTS. That is ALL mail clients, bot just Thunderbird

I originally wrote a knowledge base article on the subject (which I should seriously amend now I suppose... Could I interest you in that Toad?)

Regardless of what you configure in your mail client, Outlook will convert that as it goes through the SMTP server to your primary identity. They are unapologetic about it and claim it as some sort of security feature. But Microsoft have been claiming bugs as features since the mid 1980s

Thank you both Toad-Hall for your effort and Matt for the final explanation.

I expected that could happen but I hoped not.

I would not mark this question as solved (because it cannot be) but I think it can be closed at any time.

I am going to mark this "Solved". Solved means Google, and other search engines, get to index it. As it stands this thread is invisible and therefore of no use to others searching.

I agree with your sentiment re solved, but the greater good overrides I think. If I could just convince the powers that bee that not everything can be solved and "answered" is sometime the best that will ever occur then change might occur.