After testing many different solutions (see my question above for more information), I discarded my approach to use Email. Instead I subscribe to the RSS feeds of the newsletters and use IFTTT recipes to automatically save them to Pocket.

1. Subscribe to the feed(s) via RSS
2. Create a new IFTTT recipe

• Choose Feed trigger channel
• Choose New feed item trigger (one could adjust this by using the trigger New feed item matches)
• Enter Feed URL
• Choose Pocket action channel
• Choose Save for later action
• Add own Tags (optional)
• Add Description and finally create the recipe

3. Wait for new feed items and the recipe to trigger – Voilà

(an improvement would be marking the saved items as read)

After testing many different solutions (see my question above for more information), I discarded my approach to use Email. Instead I've subscribed to the RSS feeds of the newsletters and use IFTTT recipes to automatically save new feed items to Pocket.

1. Subscribe to the feed(s) via RSS
2. Create a new IFTTT recipe

• Choose Feed trigger channel
• Choose New feed item trigger (one could adjust this by using the trigger New feed item matches)
• Enter Feed URL
• Choose Pocket action channel
• Choose Save for later action
• Add own Tags (optional)
• Add Description and finally create the recipe

3. Wait for new feed items and the recipe to trigger – Voilà

A nice improvement would be marking the saved items as read. If I find a solution, I'll add it here.

Just if you're interested – I've shared these recipes on IFTTT: https://ifttt.com/people/kleinfreund