550 Mailbox not found or access denied

[Yadoon]

I sent emails to two emails, one illegal and one legal, may I getthe illegal one in the return err?

[sushihentaime]

This package is not actively maintained. You can refer https://github.com/go-mail/mail for the fork.

[wneessen]

This is a know bug but unfortunately won't be fixed since the maintainer has sadly passed away.

You might want to consider checking wneessen/go-mail which has addressed this issue and has dedicated error detection for failed bulk mails.

[wneessen]

This package is not actively maintained. You can refer https://github.com/go-mail/mail for the fork.

That packages is also not actively maintained anymore. It hasn't seen an update in the last 6 years.