The SMTP server would not relay a message. You may need to authenticate. (SMTP)

The SMTP server would not relay a message. You may need to authenticate. (SMTP)

not working for any business IMAP email

i purchased license for one year but i regret to get mailspring

I have the same problem with an Laposte.net french email.
Does anyone have a solution?

My error:
SMTP Last Response Code: 450
SMTP Last Response: 4.1.2 email@invalid.com: Invalid recipient address. LPN105_418

I’m having the same issue. I can see in the logs that the connection and authentication work fine, but since my mailserver is correctly not relaying the test message due to invalid recipient address, I am prevented from proceeding with setting up the account in Mailspring.
Would it be possible to change Mailspring to use my own email address as the test recipient when checking the account settings?