Computer crashed and had to reinstall Pegasus Email. Can receive emails OK, but cannot send. All attempts generate the following error:
454 4.7.1 argon@pobox.com: Relay access denied.

How can I reset my Pmail parameters to prevent this?

Please reply to stephens@pobox.com if possible. Thanks.

A common cause of relay access denied errors is that the domain part or the email address specified in Pegasus Mail is different from that of the SMTP server that you are trying to use. Go to Tool > Internet options > General tab. Check the email address specified in the "My Internet e-mail address is:" field. It's domain part should match the domain of the sending (SMTP) server host you are attempting to use.

Just another thing to check. Are you using a VPN or accessing ISP from a network that isn't their controlled link.
Long ago, checks were not required for sending mail using old port 25, but many ISPs have had to switch to require the more secure smtp port and requiring various types of authentication if accessing via no local IPs.

If using VPN software, you may be physically on a local IP of your ISP, but the VPN is making it look like a different network, so the extra authenticalion might be needed.

I'm currently in NV at moms, and long ago had to setup to use the extra authentication options or my Guam based ISP would not allow sending.

Might want to have it create a TCP log of connection. (Note: if you upload it, make sure that any password is deleted). Even encrypted password, since they can be decoded.

Hopefully, it is a minor issue.