Hello @Baptiste H  Not that shouldn’t happen. Do you use your original details to signup newsletter? May be some of these brands are filtering profile where you use keywords like test  in the user details.

Some of brands I know don’t send emails until they they more about you.

If your assumption is that Klaviyo is blocking your email then test it in your Klaviyo account.

My emails do not contain any words that could be blocked.

For example, I tried subscribing to the newsletters of my current e-commerce customers, and found several problems
- the profile is created, and in the events it says that a form has been filled in, but then no e-mail is sent (despite a live welcome flow)
- the profile is created, but then marked as “suppresses”. (with no further justification)
- sometimes the profile wasn't even created despite registration
(what I'm saying is a bit disorganized, but it comes from repeated tests)

I have the impression that after a break without subscribing to any newsletters, I can now subscribe and receive the emails, but that after several subscriptions it comes back and I end up not receiving any more emails (even though I know that the brands in question have a welcome flow).

I have the impression that the Klaviyo servers detect that I subscribe to newsletters from different brands, but the majority of which are on Klaviyo, so perhaps an act considered suspicious.

Hey @Baptiste H, I think your original assumption may be correct. I suggest reaching out to Support to investigate this further for you.  

Thank you @kaila.lawrence 
I've already contacted support but unfortunately without a convincing answer...
I'll try again!