Generally, if some of your emails bounce, but others do not, then DO make sure that your IMAP and SMTP settings are both from the same host. You can no longer use a different outgoing server (SMTP) from your email address.

That is, if your email is myname@godaddy.com, and you get your email at IMAP.godaddy.com, then you MUST _send_ your email from the same server: SMTP.godaddy.com, and log into it properly. You cannot send from myname@comcast.com, nor can you send from someOtherName@godaddy.com without violating SPF and DKIM checks.

The result will be that your emails will bounce, if you’re not properly set up.

So: match up your IMAP and SMTP servers, and the problem will go away.

More:

DMARC, which stands for “Domain-based Message Authentication, Reporting & Conformance”, is an email authentication, policy, and reporting protocol. It builds on the widely deployed SPF and DKIM protocols, adding linkage to the author (“From:”) domain name, published policies for recipient handling of authentication failures, and reporting from receivers to senders, to improve and monitor protection of the domain from fraudulent email.

A Sender Policy Framework (SPF) record is a type of Domain Name Service (DNS) TXT record that identifies which mail servers are permitted to send email on behalf of your domain. The purpose of an SPF record is to detect and prevent spammers from sending messages with forged From addresses on your domain. https://www.godaddy.com/help/what-is-an-spf-record-24605

DKIM (DomainKeys Identified Mail) is another technique to help prevent spam. It’s complex: here’s a description : https://blog.returnpath.com/how-to-explain-dkim-in-plain-english-2/

Probably more than you wanted to know.

Tracy