The recommended way to enable or disable vacation messages during your absences is through the Roundcube webmailer. Here is how it works:
Login on https://email.ee.ethz.ch/
Click on the Settings button.
In the Settings column choose Vacation.
Fill out the Reply message form:
Subject of automatic reply message
Body of automatic reply message
Date and time when automatic vacation messages should start. If you leave the time empty, it will be set to the start of the day.
Date and time when automatic vacation messages should stop. If you leave the time empty, it will be set to the end of the day.
Whether this vacation recipe should be enabled or not. Please note that an enabled vacation message only runs within the time slot defined through Vacation start and Vacation end.
Further parameters can be set on the Advanced Settings tab:
Reply sender address
Vacation messages will contain this address in the emails From field.
My email addresses
An absence message will only be sent for emails directed to (To/Cc/Bcc) one of these email addresses. This makes sure that no absence messages will be sent for emails you receive through mailing lists or similar ways. The button Fill with all my addresses fills the list with all identities you defined in roundcube.
A person sending you several emails during your absence will only get one absence message within these number of days. If you do not enter a value, it will be 7 days by default. The minimum value is 1 day.
Incoming message action
Defines what should be done with incoming emails during your absense. You have the following options:
Keep: Treat incoming emails as usual.
Discard: Incoming messages are deleted.
Redirect to: Redirect message to some other address.
Send copy to: Keep message and send a copy to some other address.