For time-sensitive offers like webinars or sales, send an initial email in the morning and a follow-up with heightened urgency later in the day. This tactic builds momentum and captures users who missed the first message, significantly increasing sign-ups and sales despite the higher frequency.
Marketers often become overly cautious due to a few aggressive unsubscribe complaints. The reality is this vocal minority is not representative of your entire database. The significant conversion boosts from more assertive tactics far outweigh the minimal loss from people who were likely unengaged anyway.
Marketers are immersed in their own campaigns and assume their audience shares that awareness. However, even close followers are busy and will miss most messages. This was proven when a marketing expert's close friend completely missed his book launch despite heavy promotion, justifying aggressive and repetitive communication.
The effectiveness of sending two emails in a day is not just about frequency, but about narrative progression. The first email should create general urgency (e.g., "24 hours left"). The second, later email should introduce specific scarcity to trigger immediate action (e.g., "almost sold out" or "only 80 spots left").