Lack of non-compete

I was terminated as an employee 6 months ago
by a consulting and training firm, where I
had been employed for 20 years. In those
20 years, I had never signed a contract of
any sort. There was an employee handbook, but it did
not mention non-compete whatsoever.
I was immediately re-engaged by this same company
as an outside contractor/consultant, being
paid by the job (each job has it's own agreement
as to fees and time).

My new consultanting contract with this firm
specifically states that I can have other
customers, and that either party may leave
the contract with 30 days notice without
prejudice. There is no non-compete clause
whatsoever.

I have just taken fulltime employment with a
competitor, as a salaried employee. I intend
to email my colleagues in the field, including
several thousand former or current customers
of the first company. I have given my 30 day
notice to them. This email will not mention
the name of my new employer, just that after
such and such a date I will no longer be able
to service their needs (as customers of my old company)
and that I have taken other employment in the same field.
These contact email addresses have resided in my personally owned
computer for many years, and I do not intend
to access the company's customer database.

The question: May I send this type of email
to current customers of my original company?

What about former customers, no longer doing
business with the former company?

Thanks!