550 - Please turn on SMTP Authentication in your mail client
 

I sent an email from Thunderbird and got an undeliverable reply as follows. SMTP on Thunderbird is set to use port 465, SSL/TLS, my regular FastMail identity, and my Thunderbird application password. Authentication method is set to Normal password.

<info@bushbabyglen.com>: host mail.bushbabyglen.com[66.147.244.59] said:
550-Please turn on SMTP Authentication in your mail client.
550-wout5-smtp.messagingengine.com [64.147.123.21]:51893 is not permitted
to 550 relay through this server without authentication. (in reply to RCPT
TO command)

What do I need to do to fix this?

Is this repeatable?
Just tried sending an email to myself with my TB and it worked ok.

By the way I don't think you want that email address in a public forum. You should probably censor that out.

Try port 587

Port 587 fails. Error reads...

Sending of the message failed.
The message could not be sent because the connection to Outgoing server (SMTP) smtp.fastmail.com was lost in the middle of the transaction. Try again.

Yes, it is repeatable. I can also send successfully to myself. The email address is a publicly available booking site.

Try a different security setting with port 587 starlets or what ever it called sorry cant remember.

Maybe try a new app password.

I have raised a ticket and will post any developments.

550-wout5-smtp.messagingengine.com

Should that be fastmail.com?

This looks to me like a FastMail restriction that sending of messages between FastMail and the destination MX server must allow encryption. All major mail services do now provide this, but it seems possible that mail.bushbabyglen.com does not.

Do you have smtp.messagingengine.com in your account settings as it should now be fastmail.com

imap.fastmail.com for incoming and smtp.fastmail.com for outgoing.

I just tried sending to the target address from the FastMail web interface and got the same error so it's apparently not a Thunderbird issue.

ok, I checked their email address it states...Unverifiable

Perhaps change it to admin or sales

If you look at their contact us page they have a different email address listed: bushbabyglen@gmail.com