The problem is that we have to specify a SMTP port for them to work while none of the following ports worked for us:- 25 with no encryption- 587 with TLS | Auto. Used “smtp.office365.com” as the outgoing server and "My outgoing server requires authentication" is also checked.
To rule out a problem with your device, send a test email to check your connection to Microsoft 365 or Office 365. To send a test email, follow these steps in the article, Use Telnet to Test SMTP Communication. If you can't connect to Microsoft 365 or Office 365, your network or ISP might have blocked communication using port 25.
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Regardless, if the IBM SMTP server is working for outside domains, why isn't it working for our own? That's not spoofing, that's just a 'from' address. If it has it's own server it would need outbound port 25 allowed through your firewall and it would not need any other settings at all, just the address you want to send from and to. If you are providing an SMTP server (the relay) then it is not using a built in SMTP server.
Wait a moment (30 sec for me) and the problem is solved: sending email with SMTP is working with Thunderbird. Here a solution that solved the problem for me : You must be an Office 365 admin. Open the Microsoft 365 Admin Center (web page) and go to Users > Active users.
Generally when we see this type of error, it means that your site’s hosting provider is blocking the port you need (in this case, port 587). This isn’t uncommon — many hosts block ports by default as a security measure. So the best next step is to reach back out to GoDaddy to ask them to look into this for you.
Mandatory requirements for SMTP Relay with Office 365. The sending app must connect to the Office 365 servers on port 587; The application which you are using for sending the emails must support TLS; The sending app must authenticate with Office 365. The “SMTP relay server” that wants to relay mail to the Office 365 mail infrastructure will need to provide credentials (username + password) using the basic authentication protocol.
Sysadmin. To smtp over office 365 you need an authenticated user and port 587 to relay on. This would avoid your internal smtp relay on prem. 2. level 1. markkrj. · 3y. Had a similar problem after migrating from eop to o365... Solved it by creating an local smtp server (postfix).
Use direct send (Option 2) or Microsoft 365 or Office 365 SMTP relay (Option 3) for sending mail instead (depending on your requirements). Use an on-premises Exchange server (or another SMTP email server) if your device is unable to meet the previous requirements for connecting to Microsoft 365 or Office 365.
Office 365 (Office365 or o365) is an online productivity suite that is developed by Microsoft. Office 365 contains online and offline versions of Microsoft Office, Skype for Business (previously: Lync) and Onedrive, as well as online versions of Sharepoint, Exchange and Project.