A huge majority of users use free webmail providers, and the biggest players in that space all allow Oauth access to email. Oauth can be scoped down to just the access you need, whereas if you give out IMAP creds those can be used to wipe somebody's email account.
Also, at least in Gmail's setup [0], the IMAP password seems to be your "Gmail password", which is the same thing as your Google account password. Don't ask for this. You don't want to have these passwords enter your company's infrastructure.
[0] https://support.google.com/mail/answer/7126229?visit_id=6368...
I actually just checked the storage price, and I notice that at some point I added a $2/10,000 charge to the equation at some point, which is almost all of the charge price. I'm going to remove that tomorrow, since it was probably just paranoia and not actual cost plus margin.
- Offer a calculator so that people can estimate their own cost. A small improvement, probably not significant impact.
- Offer a customer to enter their current IMAP creds, give an accurate estimate based on past usage. A big improvement, but which would require significant trust from the prospective client. Hard sell.
- Offer a guarantee of some kind. "If you don't come off cheaper with Purely, we'll make up for the difference". Reassuring, but increases your risk.
- Up the price of storage, and eliminate the price of traffic. Storage is probably an imperfect but adequate proxy for total usage price, given that the pattern nowadays is to archive rather than delete (non-spam) email.