Office 365 Authenticated SMTP (Not OAuth)

Hi all,

I have noticed a number of queries on the support forums about connecting PostSMTP with Office 365 email accounts.

Here are the settings that I use for Office 365 SMTP. I find these work pretty reliably:

• Outgoing Mail Server Hostname: smtp.office365.com
• Outgoing Mail Server Port: 587
• Envelope-From Email Address: your Office 365 email address
• Security: STARTTLS
• Authentication: Login
• Username: your Office 365 email address
• Password: your Office 365 email password

It is important to note that if you try and set a different email address under Message > Email Address, your outgoing emails are likely to be rejected by Microsoft and fail. This will normally produce an error message.

You must also have ‘Authenticated SMTP’ enabled for your account in the Microsoft Admin Centre. This is a fairly new option that has been added, and is usually on by default. If you are having problems you might want to toggle it off, save, and then back on again (and save!) The setting can be accessed by clicking on the user in the Microsoft Admin Centre, and then Mail > Email apps > Manage email apps > Authenticated SMTP.

Hope this helps. If you do have any further problems please do create a new thread in the support forums, and we will do our best to help. Please avoid replying to this thread.

Kind Regards,
Tim