There is a limit as to how many characters allowed in the TO: field. May cutoff a few addresses - sub 1024 IIRC approx 920. 

No easy way to tell due to email address vary in length. 

BCC: may be better (same restrictions) yet will not disclose everyones address. 

Food for thought.

Is there a simple way to send an e-mail to all entries in my address book?

Probably not. An address book is meant to be used as a reference and includes email, tel no., and home address options. What you need to do is set up is a distribution list, which only contains email addresses.

I don't know if there is a utility that allows you to harvest email addresses from an address book though.

[quote user="sirob"]Is there a simple way to send an e-mail to all entries in my address book?
[/quote]

Pick your poison...

All in To: field:
Open Address books (F3).
Select desired address book in Description panel (Up/Dwn).
Press Tab to jump to the Name panel.
Select all entries (Ctrl+A).
Press "Send mail" button.

All in To:, Cc:, or Bcc: field:
Start a New message (Ctrl+N).
Place the cursor in desired field (To:, Cc:, Bcc:).
Open Addressbook (F3).
Select desired address book in Description panel (Up/Dwn).
Press Tab to jump to the Name panel.
Select all entries (Ctrl+A).
Press "Apply" button.

All in To: field:
Start a New message (Ctrl+N).
Open Addressing Center (Ctrl+Shift+T).
If desired address book is not selected in Description panel, press Tab [x6], then  (Up/Dwn).
Press Tab to jump to the Name panel.
Select all entries (Shift+Dwn).
Add the selection to "Current addresses" panel (Alt+A).
Press "OK" or Tab, Enter.

For all in Cc: field, above except;
Open Addressing Center (Ctrl+Shift+C).

I have used Distribution Lists with great success... you can find them in the pmail folder.  They are text files named *.pml.

Here's a typical layout: 

\TITLE pooldrivers

\SENDER Everybody

\READING Y

\DELIVERY Y

\NOSIG Y

address1@isp.com 

address2@otherisp.com

(etc.)

***************************************************

I have found it easiest to manually create these text files, but I think you can also build them from within Pegasus.  I have several set up here at work for various subgroups of employees.

Good luck! 

[quote user="Guy"]

[quote user="sirob"]Is there a simple way to send an e-mail to all entries in my address book?
[/quote]

Pick your poison...[/quote]

Nice one! I did not realise you could do that.