files with attachments hang in outbox, sent repeatedly until manual intervention occurs

Files with attachments sometimes (not always) get hung up in the Outbox.  Recipients receive many copies of message but message is never deleted from Outbox nor recorded in the Sent folder.

Running version 7.2.34062.0 against a Comcast imap account on Windows 10 Home.

Does not always happen but when it does, the only fix seems to be to manually delete the message from the Outbox.  When I manually delete from the Outbox, emclient does NOT record a copy in the Sent folder.

I see several threads apparently describing similar problems over the last several years.

Is this a known issue with no fix?

First you can check if you have the correct settings for your server. Go to Menu > Tools > Accounts and click on the SMTP tab. For whichever port is recommended by your provider, use the corresponding security policy:

Port 587 = Force usage of SSL/TLS
Port 25 = Use SSL/TLS if available
Port 465 = Use SSL/TLS on special port (legacy)

All settings appear to be correct.  Email messages without an attachment are sent with no issues.  Emails with an attachment seem to hang up in the Outbox and never move to Sent even though recipient receives multiple copies

Who is your email provider, and what version of eM Client are you using?

From the initial post:

Running version 7.2.34062.0 against a Comcast imap account on Windows 10 Home.

Sorry Bruce, somehow I thought it was someone else commenting. Must be old age.

Did you change the SMTP port to 587 with the security policy set to Force usage of SSL/TLS?

Did you try upgrading to a more recent version and see if there is any difference? The current release is 7.2.36908.

No worries, I know there are lots of threads to follow.
I appreciate the suggestions and followup
Interestingly, when I check for updates I get message that no new updates are available, thus my impression I was on latest version.

I will check and see how to download latest and get it installed.

Current setting is port 465 and use SSL/TLS on special port (legacy).  This is result of clicking Fix Settings button somewhere along the line

OK, installed latest version, used suggested SMTP settings for port 587, no change in behavior.
Emails with attachments hang up in Outbox and and never move to Sent even though recipient receives multiple copies

You could also try another port. Although it has been reassigned, many providers still prefer to use port 465 for SMTP. Change it to that and make sure the security policy is Use SSL/TLS on special port (legacy)

That was the previous setting for SMTP, prior to making the change to 587/forced SSL/TLS
I will change it back to that setting but don’t expect any different behavior.