CC News, which has been running for more than a decade, includes a round-up of key announcements, dates, publications and other notices from the commission.
Historically, the only recipients were the one email address held by the commission as the main contact for each individual charity, and any other individuals that had actively signed up to the mailing list.
The summer edition of CC News was received by about 137,000 people. Trustees that received it were encouraged to share it with fellow board members.
However, many of the 164,000 registered charities do not have email addresses listed, and a significant number give generic email addresses that might not be accessed by trustees.
CC News 48, the autumn edition sent out last month, went to 222,000 people, because the commission decided to send it to all trustees for whom it had email addresses. The regulator is now encouraging charities to get all trustees to sign up to receive the email.
Charities listed on the Charity Commission’s online register account for a total of more than 943,000 trustee positions, although it is not clear how many people have been counted more than once because they are trustees of multiple charities.
A spokeswoman for the commission said: "CC News keeps trustees up to date with new guidance, reports and alerts, and reminds them of key commission messages, such as the importance of submitting serious incident reports and filing accounts on time.
"We decided to increase the distribution of the newsletter to all trustees for whom we have an email address to ensure that all those who have a role in governing charities are aware of these issues and their legal duties and responsibilities. Trustees should ensure that they read CC News and encourage their fellow board members to sign up to it."
Separately, the Office of the Scottish Charity Regulator has proposed to build up a database of trustees and their contact details so it can contact charities more easily.
Responding to the OSCR’s consultation on this and other proposals, the Scottish Council for Voluntary Organisations said the database could be useful but would be expensive to construct.