I do know the actual answer. Only peripherally related to heartbleed.

The answer is several of the biggest email providers, AOL, Gmail, Yahoo, and a few others, have finally decided to institute a white list for email. This means that email that purports to come from aol.com, for example, that isn't really coming from AOL hosts, will be rejected out of hand by the other participants in the white listing. Same is true of gmail, and yahoo email.

The basic concept here is to kill off the spoofing email. It may have consquences on listservs.

On Apr 26, 2014, at 10:54 PM, Marc Perdue <mcperdue@GMAIL.COM> wrote:

> I don't know the actual answer, but it appears that Google has made some
> modifications to its spam filters, probably in response to the recent
> Heartbleed issues. At first, I was getting these mostly in response to
> listmembers who had Yahoo and Aol accounts. It's ironic that the filters
> are suspicious of Google's own gmail accounts.
>
> Marc P.
>
>
> On Sat, Apr 26, 2014 at 10:47 PM, bernie <1234bjs@gmail.com> wrote:
>
>> Yes I have and I just got one.
>>
>> "This message may not have been sent by: dhanson928@gmail.com "
>>
>> I was wondering the same thing. Why now all of a sudden?
>>
>> Bernie
>>
>>
>> On Sat, Apr 26, 2014 at 7:44 PM, Don Hanson <dhanson928@gmail.com> wrote:
>>
>>>  Has anybody else recently began getting these Gmail  "!Warning! May not
>>> have been sent by ____________......" message headers with a lot of
>> vanagon
>>> list  emails?   They began appearing a few days ago,  on top of lots of
>> the
>>> posts from Vanagon List that I've been getting.  Gmail has a convoluted
>>> explanation in a drop down menu that I don't follow, being a
>>> cyber-challenged...I  don't think I have changed anything in my settings
>> to
>>> cause these highlighted headers to began appearing...but ....?
>>>
>>>  Don Hanson
>>>
>>