When I use reset password the mail is sent to our smtp server and it is sending it to the target outlook user but outlook is not delivering the mail.
Other mails from xwiki are working but not reset password mail.
Only additional thing I see in reset password mail is “x-mailtype reset password” header, is this blocking the mail.
I am using 14.4.1-postgres-tomcat docker image for the deployment.
I had recently heard a similar complaint; however with a custom “welcome” mail, but the same problem: outlook addresses do not receive the mail.
I guess this has something to do with the “zero-spam” policy of outlook; at the risk of discarding legitimate mails they block everything that looks like spam. In this case I suspect the mail is classified as “phishing” - an attempt to trick people on a fraudulent website to enter their credentials which is then used to hack their account on another web site.
As in my case the suspected x-mailtype reset password header is not send, I guess it has something to do with the mail contents. Unfortunately I could not get the users having that problem into investigating closer yet (I have no access to their mail server, etc.) I hope they come back to me later.
Can you try to change the content of the “Password reset” mail and change the words in there to see if the mail gets through if it does not mention “password” and such?
(This might make the mail unintelligible for the receiving users, I just ask for testing what trigger the issue. You can reset the page via the page history to the original content any time.)
The page containing the mail can be found at …/xwiki/bin/edit/XWiki/ResetPasswordMailContent?editor=object
If you have any questions about my idea how to debug this, or any other information about the issue, please let us know. 
After changing the wording from “Password” to something else it’s working.
Thank you for the support.