How often is too often? How often is not often enough? Your subscribers know best how frequently they want to hear from you They'll let you know by means of unsubscribing.

To prevent that, consider asking them for a perfect frequency, test heavily, and maybe ask those who unsubscribe for their reason.

To get started, consider this rule of thumb, though:

• Everything less often than at least every other month is not often enough. People will forget about you, and the surprise of a newsletter from you showing up after a year will probably result in a surprise unsubscription.
• Everything more often than once a week is too often unless your subscribers specifically agreed more frequent mailings. People will get tired and annoyed by your emails, and unsubscribe even if they like your content.