TL;DR: You may see a $1 charge appear on the credit card you have registered at FastMail. This is temporary as part of a conversion process and will completely disappear within a few days. There is nothing you need to do.
We're currently in the process of moving our credit card payment gateway to a new provider, Global Collect. Global Collect are a large and well respected provider of international payment services that will allow us to support more cards and payment methods in the future.
As part of the switching process, we're securely converting all credit card details from being stored on FastMail systems, to being stored at Global Collect. By doing this, we'll be able to remove all credit card details from our system, something we've wanted to do for a while.
However there is one issue. To enter the credit card details into their system, we can't just enter them as is, we have to enter them with a transaction so that the card can be checked and authorised.
We're doing this by creating a dummy $1 authorisation against each card. With credit cards, it's possible to create an authorisation on a card, but never actually complete the transaction. After a few days the authorisation times out, and the money is never actually taken from the account.
However the $1 authorisation is still something that banks will do their usual fraud checks against, potentially alerting you to the transaction via email or a phone call, and potentially having the transaction appear (temporarily until it time out) on your online statement. Because of different gateways, the payment on your statement may appear to come from either "FastMail" or "Opera Software".
If you do see something like this occur on your credit card, then there's no need to worry. This is just a consequence of the transfer, and the $1 charge will completely disappear from your credit card in a few days. In some cases, it's also possible that there may be two separate attempts to charge $1, because Global Collect will route payment attempts through multiple gateways if one appears to fail. Again, there is no need to worry about this.
We're sorry for any inconvenience this has caused some people, we didn't realise up front the full issues this would cause some users, especially the surprising contacts from their bank, we thought it would be basically an invisible process for all users.
At this point there is nothing you need to do. If your bank contacts you about the charge, you should tell them it's ok and to process it. The $1 charge will completely disappear after a few days.
Once the conversion is complete, all FastMail payment services should continue as normal. Account renewals should be automatic (unless you've explicitly disabled them), and you should be able to add funds/upgrade/downgrade from the appropriate Options screens.
Long term we want to add additional payment options as supported by Global Collect, the first of these is likely to be Paypal sometime in a few months.