DatedMail
DatedMail is a PowerShell module intended to provide a simple way for expiring email addresses. Ultimately this should reduce spam as mail addresses are only available for a certain amount of time.
This can be very useful for example if an imprint email address is required.
Note
For this guide you should be familiar with the basic concepts of
License
All relevant legal information can be found here
Prerequisites
DatedMail uses Sieve filters to reject mails. Therefore the spamfolder needs to be enabled. So first we check that the spamfolder is correctly enabled.
[isabell@stardust ~]$ uberspace mail spamfolder status
The spam folder is enabled.
Next we need a new mailbox that is exclusively used to forward or reject mails based on the expiry status of the mail address. In this example we use the mailbox temp.
Of course other names can be used. Note the name choosen for the installation:
[isabell@stardust ~]$ uberspace mail user add temp
Enter a password for the mailbox:
Please confirm your password:
New mailbox created for user: 'temp', it will be live in a few minutes...
[isabell@stardust ~]$
Installation
Install the PowerShell module
Launch PowerShell and use Install-Module to install the DatedMail module. Confirm the Untrusted repository warning with Yes.
[isabell@stardust ~]$ pwsh
PowerShell 7.2.24
Copyright (c) Microsoft Corporation.
PS /home/isabell> Install-Module DatedMail
Untrusted repository
You are installing the modules from an untrusted repository. If you trust this repository, change its InstallationPolicy value by
running the Set-PSRepository cmdlet. Are you sure you want to install the modules from 'PSGallery'?
[Y] Yes [A] Yes to All [N] No [L] No to All [S] Suspend [?] Help (default is "N"): Y
PS /home/isabell>
Configuration
Initialize the module
Still within the PowerShell console perform the initial configuration. If you choose another name then temp for your mailbox make sure to enter it here.
PS /home/isabell> Initialize-DatedMailConfiguration -MailAddressPrefix "temp+" -MailAddressDomain "isabell.uber.space" -SieveFilterPath /home/isabell/users/temp/sieve/datedmail.sieve -ForwardingEmailAddress isabell@uber.space
PS /home/isabell>
Configure the expiration timer
Once a mail address expires, it needs to be removed from the sieve filter. This is the job of the command Update-DatedMailAddress. We configure a new cronjob which will run this every hour.
The command to call is /usr/bin/pwsh -Command "Update-DatedMailAddress".
PS /home/isabell> crontab -e
Add the following line to your crontab: 44 * * * * /usr/bin/pwsh -Command "Update-DatedMailAddress". This will call Update-DatedMailAddress every hour on minute 44. Then save and close your crontab.
Finishing installation
Create your first expiring mail address
To add your first expiring mail address, call New-DatedMailAddress -ValidDays 8 -ReturnMailAddress
PS /home/isabell> New-DatedMailAddress -ValidDays 8 -ReturnMailAddress
temp+72lv4xdbh4yqu40@isabell.uber.space
PS /home/isabell>
In a scenario where you regularly roll over to a new expiring mail address, you could also export the newly generated email address to a file for further processing:
PS /home/isabell> New-DatedMailAddress -ValidDays 14 -ExportFilePath /home/isabell/dated.mail
PS /home/isabell> cat dated.mail
temp+yt3ju2ya17pvp28@isabell.uber.space
PS /home/isabell>
Enable the Sieve filter for the mailbox
Now what’s left to do is to enable the filter on the temp mailbox, so it is getting applied:
PS /home/isabell> New-Item -Path /home/isabell/users/temp/.dovecot.sieve -Value /home/isabell/users/temp/sieve/datedmail.sieve -ItemType SymbolicLink
Directory: /home/isabell/users/temp
UnixMode User Group LastWriteTime Size Name
-------- ---- ----- ------------- ---- ----
lrwxrwxrwx isabell isabell 16/02/2025 17:23 43 .dovecot.sieve ->
/home/isabell/users/temp/sieve/datedmail.sieve
PS /home/isabell>
Best practices
The mailbox used (in our example temp) must not be used for any other purpose.
The sieve script generated by DatedMail should not be updated by hand. Any change will be overwritten whenever a new expiring mail address is added, or an existing address expires.
If you want to use expiring mail addresses for websites, you should automate the deployment of new mail addresses, too. E.g. create a script that calls New-DatedMailAddress and then copy the new mail address to the correct place so it gets served to website visitors.
Tuning
You can adapt the cronjob to your needs. Typically running once an hour should suffice, but more frequent runs are also possible.
Updates
Note
Check the update feed regularly to stay informed about the newest version.
To update to the newest module version just run Update-Module.
PS /home/isabell> Update-Module DatedMail
Untrusted repository
You are installing the modules from an untrusted repository. If you trust this repository, change its InstallationPolicy value by
running the Set-PSRepository cmdlet. Are you sure you want to install the modules from 'PSGallery'?
[Y] Yes [A] Yes to All [N] No [L] No to All [S] Suspend [?] Help (default is "N"): Y
PS /home/isabell>
That’s it. Next time you run any command the new version is automatically used.
Debugging
If something fails you can try to debug using the -Debug and -Verbose switches with the PowerShell commands to get more output from the commands.
Backup
The only data you should regularly backup the configuration in your .config folder (~/.config/DatedMail/)
Tested with DatedMail 1.0.0, Uberspace 7.16.5
Written by: Marvin Dickhaus <https://marvindickhaus.de>