Validity to Acquire 250ok

When I ask myself, what vendors are there in the deliverability monitoring tools space, I think of three primary vendors: Return Path, 250ok and eDataSource.

Then I ask myself, what will this vendor landscape look like in a year from now?

Because Return Path was acquired by Validity.

And then eDataSource was acquired by SparkPost.

And now, it's just been announced that 250ok will be acquired by Validity.

The times, they are a changin'.

Anybody want to remind me, what other deliverability monitoring or seedlist monitoring vendors exist today, besides all of the ones listed here? I recall there are a few smaller players but it's hard to keep track of them. I'd welcome comments and feedback pointing out other vendors in the space. It can't hurt to put together a list of potential vendors for anyone who wants to research the space in the future.


  1. Maybe an alternative question: what are the alternatives to seedlist-based inbox monitoring?

  2. is the only other one that comes to mind

  3. Inboxable by Yesmail

  4. Mail Monitor is still around and looks to have added some new products in recent years.

  5. GlockApps provides the seedlist-based Inbox monitoring, email spam checker and DMARC analytics.


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