Very bad open rates with MailWizz. It renders my campaigns useless


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Hello everyone,

I know the title is dramatic but it's true and I don't want to start the post on a bad tone so firstly I'd like to congratulate the developer for making such a powerful tool.

Now getting to my issue - To summarize: every single campaign i'm putting on mailwizz has garbage open rates, 3%, 8% or never budging above 11% open rate.

Please allow me to detail so that we don't circle the convo around domain reputation, IP score or list quality etc.:

- I have been battling this issue since I first purchased the app in late fall last year
- I have been using campaign assets which I was moving from different platforms. Literally the same exact senders (same domain, same email, same delay, same sending IP, same sending smtp relay, same copy, same every single thing)
- The above described assets were performing very well right before moving them to mailwizz (open rates ranging from 30% to 40% with just some hovering around the 20%s
- I have even sent campaigns concurrently using the same setups - while no changes to the great open rates on other platforms, mailwizz wouldn't budge over 11% with the lows being 2% or 3%
- I have tried all the options I have thought might impact sending in some way or another (force sender, increase delay to ridiculous times etc) nothing improved - every time doing my best to isolate campaigns so I could pinpoint a potential issues.

So at this point I hope it's clear I've put a lot of effort into figuring this out and it's nothing at all related to ip/domain reputation, lists or whatnot.

But wait - there is more:

Last week I thought I had a breakthrough. It's something I discovered in my desperate attempts to figure things out. It seems that when you use the "Test Template" option in the app, the mail which goes out doesn't have identical headers to the actual campaign emails that go out. And when looking at the actual active campaign headers I noticed there was a ton of additional entries which I didn't want nor I could easily disable (but that's another topic).
So I went in and modified the php files removing those headers until I managed to match the headers going out to be the same as the other platforms I'm using.
I can confirm the changes took effect, tested, double checked, triple checked... still absolutely no improvements on open rates whatsoever (again with freshly moved campaigns, not old ones)

To be honest, I'm lost, during the past months I have tried every single thing I can think of, I have put in a lot of effort into making this work, it just seems that I've hit a brick wall - everything I put on mailwizz automatically turns to garbage.

If you read this far, thank you and to anyone who has some insight on possible causes I will be so grateful for any nudge in the right direction.

It's an incredible tool that was developed and I know there must be something causing this but I'm not seeing.

Any thoughts? Anyone experienced the same?

Thank you for any responses
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@altroaltro / @Sal - sorry for the late reply, i've been busy with other tasks.
For a start, the headers are different in tests vs real campaigns for various reasons, like the fact sometimes you might test a list without subscribers and therefore you can't have subscriber specific data in the headers, but regardless, this should not matter that much in the whole scheme of things.
You said you get super low rates. If you do a test campaigns to a small list of people, say 10, and you open clicks, do all these events get tracked properly? The reason i am asking is because, a common issue is that people send super large campaigns, and mailwizz is able to deliver but then people start opening and clicking inside the campaign and all these will call urls from your mailwizz app and will put a certain load on your server, which might make your server simply drop connections because it can't handle them all. So let's start with this test and see where this leaves us, then we can debug more, i am sure is something small that causes this.
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@twisted1919 thank you for the reply.

Got it regarding different headers in test vs real campaigns. It makes sense from a technical point of view but I still think it weighs in a lot in the grand picture. One of the scenarios where I see this affecting is when you might have unsuccessful campaigns and if those campaigns yield some spam reports or some complaints, they'd drag along with them other ok/successful campaigns because those added headers point to the same origin (the domain where I have mailwizz installed is mentioned 3 times in the headers) for every single campaign email which goes out.

As for the open rates, I'm 99% certain they are tracked correctly, with the following notes:
- firstly, just to make sure, I'm not using url tracking and also disabled open tracking as well for a good bunch of them and only let the smtp relays do their own tracking (like sendinblue, sendgrid etc) and I get the opens from there
- secondly, even outside the above case, when I track opens with mailwizz as well, the emails still have tracking links added by the relays i'm using and the always match with what mailwizz is saying

Now circling back to headers part (I know.. I'm sorry :) )
There is one thing I missed which I'm trying to tackle now so I can fire another round of tests.
I was saying in my op that I disabled the headers which I didn't want and tried making them identical to other platforms I'm using where open rates are great.

There is one header which I missed and that is "Origin-Message-ID" or just "Message-ID" which right now is sent in following format:

I have found the the file doing this is the swift mailer, specifically:

3 Reasons why I'm trying to change this:
1. running out of things to cling on as to possible solutions
2. the MessageID from the other platforms I'm using is broadcasted like this: (EUMSTSJSO9U4.V61E7OOH82C43@RD00145DE35618)
3. trying to conform to "official recommendations as to how the Message-ID should be formatted ( In this case specifically, the part before the "@" should be two chunks separated by a "."

I believe there is a finger print I'm leaking somewhere which causes the low open rates and this seems like the last piece of the puzzle with my theory, everything else should be identical.

I'll come back with my findings once I manage to change that Message-ID and fingers crossed it will work some miracle.
Btw, if anyone is familiar with how swiftmailer sets that and wants to help me with this, I'm happy to pay for your time or if @twisted1919 has a quick fix to make that change happy to pay as well (or extend support via my purchase platform, any way you prefer).

Thank you
@altroaltro - these are some interesting findings, thanks for explaining in details.
The message id is something the mailer library sets automatically(swiftmailer), and as far as i know, swiftmailer is compliant as it can be.
Did you ever try sending with PHPMailer (settings > common > System Mailer) ?
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Eagerly awaiting any findings as I suffer from low open rates also but do not have any tech skills so any fix would be appreciated
This is interesting. Looking back - my opens were in the range of 12-14%, and this was before I cleaned my list. After cleaning my lists, it has dropped down to 3-4%.

The only change is that I was heavily using SparkPost's free plan till they bumped off the free plan and also me from the platform and now I am using a mix of 6 different and free third party SMTP providers of which 3 are new.