Here is what I was told about the gmail rule:

Here's a portion of what I received from one affiliate-

1) Do NOT promote using the dot method, do not encourage use of tons
of gmail addresses. No one can possibly use tons of email addresses
legitimately.

2) Do not encourage use of Roboform. Autofill is what foreign hackers
use to mass abuse US offers, and advertisers are not going to treat
you any differently if they see it happening.

*********
and

...just to CORRECT my earlier post (which I completely misunderstood)...here is a suggested way to do offers if advertisers start banning the gmail method:

You do not need a new email for every brand of survey. You can only use each email once per brand. Meaning-If you have the email 123abc@yahoo.com, you could do 1 of every offer brand on that email.
So you could do 1 MID, 1 SE, 1 GG, 1 IRC, 1 ECN, etc on that email address.

After that you would need a new email address to do another set of 1 of each brand.

*****

So, it still looks like you would need several e-mail addresses to do offers over time.

I am sorry for the confusion, but I hope this clarify things!