I don't know what your tech stack looks like, but it seems relatively trivial to build. Back in the day I built a tool for viral email lists which tracked referrals like you described.
If you consider it a long-term, integral part of your service and you can use the flexibility it's worth building it yourself. Integrating an existing service might end up costing the same number of development hours.
If however you want to provide a marketing person with the flexibility to tweak the goals (and potential rewards?) then an off-the-shelf solution might be more useful. I remember a solution in addition to the one's you already mentioned, but can't recall its name right now. Will do a little digging and follow up if I find it.
Edit: here's a service you could use: www.getambassador.com
I've always tried to be quite iterative when it comes to shipping as I feel like that's the fastest way to build something people actually want. You build something small. People use it. You get feedback. You improve and expand. You get more feedback. Etc.
With WIP I've taken this to an extreme shipping very small updates at a time. The reason for this I think is three-fold:
The todo system and streak empower me to ship daily and thus ship small things at a time. This makes me think about what the minimum functionality would look like for a certain feature.
Getting feedback from my customers (the WIP community) is really easy because we're all in the chat. I'm constantly talking to you all, getting instant feedback, and actually seeing how you use the product in real life. I don't need to rely on abstract data or one-at-a-time customer interviews. It's just all there in the chat.
Since you are all makers too, you tend to be understanding when something breaks, doesn't fully work, or isn't as polished yet. This means I can launch something quicker than I'd usually do. And some times that means finding out quicker that I'm going the wrong direction and so I can iterate quicker.
So my lessons learned are as follows:
Use WIP to motivate yourself to ship daily :D
Make sure you have an efficient way to talk to your customers. If it's difficult for your specific product I'd even go as far as reconsidering that's really the type of product you want to build.
Make sure your first users are early adopters and open to things breaking once a while. If your product is valuable enough people won't mind if it isn't as polished.
Depends on the context and specifically the relation you have with your newsletter subscriber and they have with you.
If you want it to feel personal a plain text email (or a HTML version that looks like it*) is probably better.
On the other hand, if e.g. you are a bakery and doing a sale on your newest cakes you want to include photos, etc in which case a rich HTML email would be a better fit.
- Reason you might want to go with an HTML version even if you make it look like plain text is because it gives you more flexibility in terms of adding tracking links while still making them look like regular links, etc.
Depends on their limitations* and legality of it. Usually these type of credits are non-transferrable.
If you do end up buying those credits I would write up a contract which stipulates you get your money back if those credits are taken away from you by AWS. Alternatively if the seller trusts you, you could set up a payment scheme where every month/quarter you'd share your invoice and pay only for the credits that have been used. (e.g. 50% of their value)
*AWS is known to give away a lot of free credits, but with some severe restrictions such as them only being valid for one year.
Yeah you want to make sure you're offering value so provide it free of charge first. Only start charging when it's worth paying for.
That's how #wip paid memberships started too. Same for @levelsio's #NomadList, and many other paid communities.
Some not-so-obvious ways:
A
mailto:link. You can then subscribe (with double opt-in!) people that emailed to that address. The advantage of this approach is that the user doesn't have to write their email address. Great for mobile users. The downside is that not everybody might have an email client configured and it might be a bit confusing (although you can usemailto:[email protected]?body=instructions) to show instructions to the user in the email client (bodyis automatically shown in the compose message text)Facebook Connect or one of the many other social logins. They often provide you the user's email address too. Just make double sure the user is informed they are subscribing to an email list as it's not necessarily obvious this way.
You can cancel your WIP account here: wip.chat/users/edit
I'd love to know why though!