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SendGrid as smarthost - failed in server_plain_authentication

BartJen

Hi All!

My ISP recently decided to block outgoing port 25. I've always used O365 as smarthost to relay e-mail, the downside is that O365 only supports port 25 for relaying to external recipients hence I am in need for a different solution.

I've reverted to SendGrid, hoping it would give me a solution to use as smarthost for e-mail, which it does by offering a SMTP relay feature. After confg and testing, it seems that XG does not correctly authenticate to SendGrid? 

What could be missing here making it not willing to deliver?

Supported ports by SendGrid are:

Ports
25, 587 (for unencrypted/TLS connections)
465 (for SSL connections)

Emails end up in the spool as failed:

Under General settings:

It does try to communicate, in the packet capture there is an exchange of certificates (from GoDaddy) including "smtp.sendgrid.net":



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    There is an limitation about upstream authentication.

    See known issue list:

    NC-9106 Framework part of base (deprecated) Mail notification isn't working with Microsoft Office365. Sophos Firewall supports STARTTLS and SSL/TLS to encrypt emails. However, for SMTP, it only supports PLAIN authentication, which Office 365 doesn't support.

    Configure an intermediate relay to workaround this behavior.

    __________________________________________________________________________________________________________________

  • +1 in reply to LuCar Toni

    That explains the behaviour, hope there is a uservoice for this. Thanks for the quick response!

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