Ability to delay sending email

I'm looking for a way to delay the sending of an email - not a reply (which can be done with automation and tags) but a fresh email to as few as one single recipient.

In Outlook, the Delay Delivery function allows you to delay sending the email until a time specified, provided the PC you're using is online at that time - otherwise it sends next time you log on.  No such functionality exists (yet) in Sell.

Here's why this is a problem.  For me, the single most useful feature in Sell is the ability to see when emails have been read. I am a wine supplier to the hospitality industry - typically restaurants, wine bars and cafes - and i know that the best time to get my outbound emails read and hopefully responded to is typically 11am-12pm or 3-5pm - the windows either side of my customers' serving lunch but before dinner. 

But these are also the best times to be out making sales calls (ie conducting wine tastings) with my customers, since they're outside that window when they're busy serving lunch and dinner to their customers.    

Emails sent outside those hours, or even weekends, can be so far down the inbox when these folks next log onto their work email, that both the open rate and the response rate are much lower.

At the moment, I can send using Delayed Delivery in Outlook, but i don't get the valuable feature of seeing if it's been read.  OR, i can take time away from 'customer time' to send from Zendesk.  I have even been known to prepare the email in a 3rd party app like Evernote, and then copy-and-paste the address, subject and body into the outgoing email of Sell.  But this is far less than ideal, as I'm typically out in the field and pecking at a phone or tablet, rather than a PC.  I'm also probably rushing to do it while travelling between meetings in different venues.  

If implemented, I'd used this feature a few dozen times per week.  It would be especially useful where the relationship is new and thus a more timely response during that 'honeymoon period' is so valuable - it would probably increase my sales to newer customers by at least 20% since less things would get shifted to the bottom of the pile by my customers in a highly competitive market. 

In terms of prospecting, it's hard to quantify, but possibly a 30-40% increase in getting meetings.  Functionally, it'd be like having a second "me" for a couple of hours per day.