Each email marketer has to remember overall email campaign experience is based not only on timing and content of emails themselves, but also landing experience.
Recently I've got a promotional email from an airline company saying they're opening a new destination with an extra cheap flight for a first few weeks. When I landed into their website I wasn't able to find this new destination in a destination field on a booking page. Basically they have failed to sync promotional email campaign with a website update.
Email marketers have to avoid such situations at any cost as they're ruining the rest of the efforts - all the timing, design, copywriting and management work.