O365 SMTP Authenticated Submission client protocol change



  • I got the below message from O365 admin center today:

    Starting June 1, 2018, we're introducing a limit of 3 concurrent connections per mailbox when sending emails using the SMTP Authenticated Submissions client protocol. This non-proprietary protocol is used to send email by legacy email clients, third-party software and services, and devices such as multi-function printers.
    
    Also, sent emails will now be stored in the Sent Items folder.
    How does this affect me?
    You are receiving this message because our reporting indicates your organization sends a high number of emails, using the SMTP Authenticated Submissions client protocol.
    
    When this change is implemented, multiple legacy email clients, devices, or applications may no longer be able to send emails at the same time and may experience temporary errors forcing them to retry. This change will, most likely, impact mailboxes which send a large amount of emails.
    
    This change does not impact Outlook clients.
    What do I need to do to prepare for this change?
    If your organization is impacted by this change, you have a few options:
    
    1. Use a different mailbox per application or device.
    2. If you are trying to send out bulk emails (such as a newsletters to employees) in parallel to using a 3rd party application, you may have to send it out in batches or use distribution lists. 
    3. If time is important (such as with an alerting system that could generate multiple alerts at the same time), you will need to use a third-party email delivery service that is designed to send out large amounts of emails. 
    

    We have a lot of services where we've used a standard mailbox account to send out notifications, was planning to have this changed to an internal relay server pointing to O365, not sure how does this setup works after this change.

    As an alternative option, first thing comes to my mind is to get mailgun as 10K emails are free on mailgun.

    Do you have such requirements and if so what are your plans?



  • Do you use that one specific protocol?



  • Regular SMTP authentication, yes



  • Do you use multiple concurrent connections though? As long as it is 3 or less, you will not be impacted.



  • I have a client on O365 that sends a few thousand emails a few times per day.

    I had to setup a postfix server to send directly because I was hitting the O365 limits for numbers of email sent.



  • @jaredbusch said in O365 SMTP Authenticated Submission client protocol change:

    Do you use multiple concurrent connections though? As long as it is 3 or less, you will not be impacted.

    And three is a lot for email.



  • The O365 account is used at multiple services (network monitoring, snipeit are some of them). I guess mailgun would be a good choice to avoid this altogether. The free version supports 10K mails


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