Incorrect STARRTLS response to EHLO

[Former user]

MXToolbox reports that TLS is not supported. MXToolbox is expecting "250-STARTTLS" (with a dash) in response.

Manual issue of EHLO command returns "250 STARTTLS" (with a space, no dash)

[Scott MacDonald]

You've enabled LE to provision a certificate? Or installed one on in your Poste.io configuration?

[Phastor]

I’ve enabled LE and connection diagnostics verify that it is valid.

I think this is a matter of Poste not returning what MXToolbox is expecting when it announces the commands and protocols it supports (the missing hyphen in the STARTTLS line.) This is just an inexperienced observation though.

Here’s the line from MXToolbox that is making me think it’s this.
“Your SMTP email server does advertise support for TLS. After connecting to your mail server we issue an EHLO command to introduce ourselves and to request that your server announce which commands and protocols it supports. Your server's response did not include "250-STARTTLS" indicating TLS support.”

[SH]

It is definitely MXToolbox error - please report to them.

Both variations are valid per SMTP specs - hyphen only marks if its last line of response or not