Yes, if they do use your servers, exclusively.  I have also seen some 
local access providers say use our servers to send email no matter what 
the from address and their local help desk will guide the user to setup 
their email client to do that.

Lyle

On 7/6/2012 8:59 AM, Paul M. Beck wrote:
> This shouldn't matter as long as they are using our server(s), correct?
> All of our clients have been setup to send receive via SSL on our servers only.
>
> On Jul 6, 2012, at 8:53 AM, Lyle Giese wrote:
>
>> On 7/6/2012 8:43 AM, Paul M. Beck wrote:
>>> We have run into an issue with a large ISP indicating that SPF records should only use ~all and never -all
>>> Has anyone found -all to be problematic?
>>>
>>> Paul
>>>
>> -all means this is an exclusive list of where legit email can come from.  Unless you have 100% control over your users, they will use whatever/where ever to send email and you will run afoul of this one.
>>
>> Lyle
>>
>>
>