Duplicate emails being sent by Mailer and Notifications

No. Just one welcome email is sent.

Ok, then it absolutely sounds like a plugin doing. Specifically sounds like it could be CB Profile Update Logger unless you're acting on profile update with CB Auto Actions.

One other question. Mailer "priority" is populated with "3". That couldn't be doing it. Could it?

You have all your mailers with the same timeframes? If that's the case then it's going to likely send all of them at once as that's how you configured it. You need to stagger them as I've shown above so they do not overlap.

No. There are 7 different emails each with a different time frame trigger - upon activation, 1-day, 5-days, 9-days, 12-days, 14-days and 15-days after subscription. Each one these is then being sent 4 times all in a batch.

Please PM backend super administrator login credentials and will take a look. The only way for it to send multiple like that is for it to be configured to do so.

PM sent.

I believe priority is simply a grouping feature to group mailers together as the query will order by priority then by ordering. In short it's to allow X to email before say Y.

Your mailers absolutely have some overlap configured as follows.

Mailer 1
Automatically send message at following date: at
But do not send message if it's later than: 5 years after

Mailer 2
Automatically send message at following date: 1 day (24 hours) after
But do not send message if it's later than: 5 years after

Mailer 3
Automatically send message at following date: 1 week (7 days) after
But do not send message if it's later than: 5 years after

Mailer 4
Automatically send message at following date: 12 days after
But do not send message if it's later than: 5 years after

Mailer 5
Automatically send message at following date: 13 days
But do not send message if it's later than: 5 years after

If you send the email 14 days after someone subscribes they will receive all 5. You need to adjust "But do not send message if it's later than" to stop the overlap. I suggest the following.

Mailer 1
Automatically send message at following date: at
But do not send message if it's later than: 1 day (24 hours) after

Mailer 2
Automatically send message at following date: 1 day (24 hours) after
But do not send message if it's later than: 1 week (7 days) after

Mailer 3
Automatically send message at following date: 1 week (7 days) after
But do not send message if it's later than: 12 days after

Mailer 4
Automatically send message at following date: 12 days after
But do not send message if it's later than: 13 days after

Mailer 5
Automatically send message at following date: 13 days after
But do not send message if it's later than: 5 years after

The alternative is a potential bug with "Priority" usage and have informed beat of this topic.

Thanks Kyle. I see the logic of that now.

One last question, there are two settings for:

Maximum messages in total (0=unlimited)
0

Maximum messages per customer (0=unlimited)
0

If I set "per customer" to "1" would that then limit the send of that email one time to that customer?