SMTP relay o365 (Send email from application or device to o365 in hybrid mode)

[Kais_mbarki]

Hello,

can i send email to o365 with direct send method in hybrid configuration ?

the mail its send to local user in domaine o365 but not send to external user 

I have an exchange server 2013 hybrid with o365 and the MX is on o365 ( the traffic mail work correctly ) 

i put the  public @ip adresse in receive connector .. the mail its send to local user in domaine o365 but not send to external user from application when i want send notification to externe user 

we want to modify all notification in exchange to o365 , after that we remove the exchange 

i read this article and i configure the 3rd option 

https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/how-to-set-up-a-multifunction-dev...

thank you for help 

[#2]

@Kais_mbarki 

Hi, in an Exchange Hybrid environment, the preferred method to SMTP relay is through the Exchange Hybrid server itself. 

I note that you are planning to remove your Exchange server?  If you do this, and continue synchronising your AD to Azure AD, then you will be putting yourself in a position where you are not supported by Microsoft.

So I would recommend keeping at least one Exchange Server to act as Management Server and SMTP relay.

[#3 · Accepted solution]

Although I do agree with you Peter on leaving the last Exchange server in place, the option stated by @Kais_mbarki should work.
Requirements are creating a connector in EXO from his WAN IP (or option e-mail server of your org in the EXO ECP) to Office 365 and adding a whitelist entry for the IP in EXO as well.
If you then specify your Office 365 "MX record" so your-domain-com.onmicrosoft.com in the app as the mail server with port set to 25 and SSL to ON it should work.
I have several clients who are using Office 365 as a relay server this way.
By the way, I wouldn't suggest using the authentication method anymore because basic auth support will be discontinued in the future.

[#4]

@BemmelenPatrick 

I do agree it should work.  Have done so many times this way myself.  I have found this method can be inconsistent and unreliable at times however.  But yes, it does work.

[#5]

Thank you,
it worked following the change from organization type connectors to mail server type