I was just checking so I am not missing any important information.
I know it is possible to start a certain profile via command line,
and some people make use of it by starting it via task scheduler.
This is externally initiated automation.
I will not forbid that, but there will be no official support from MailStore,
this is Windows functionality, so we have no control over the reliability.
Concerning your issue " unable to read message headers for a message in folder with date <?>…"
it technically means that a certain mail cannot be requested, as it contains unreadable data.
How come? That is the symptom we need to find out.
As stated before, AV solutions can be a cause when they have features “sneaking” into mail and web connections searching for threats.
The idea is good, but from a technical point of view, this is a “man-in-the-middle-attack”.
A secure connection is intended to ensure that only two specific sides communicate. A third party app sniffing is a security breach. Many modern systems detect such behaviour, so GMail might be refusing the connection all of a sudden because of a potential attack.
Also, your Norton AV might find suspicious content in a mail and therefor refuse to continue passing on the data - MailStore Home is then of course not able to read anything anymore.
Some AV solutions still operate although they have been deactivated - strange, but seen.
So it is safer to officially deactivate such features or create exclusions in the solution preferences.
In your case with Norton, there should be features “HTTPS Inspector” and “M-Mail Antivirus”.
To narrow down the issue, you might want to deactivate those two features temporarily and monitor the results.
The other possible cause for such an error message could be that there actually is a defective mail in the mailbox that cannot be read.
Last but not least the connection might be disrupted during archiving.
Does your internet router have a system log where you can check whether there have been unexpected disconnects in a simliar time the error occurred?