I've got a client that has been trucking along with their IP warming plan that I created. But, due to unforeseen circumstances, they have to skip a week of email sends during their IP warming period. What are the impacts (positive/negative) in skipping a whole week and resuming the following week?
It's more a neutral impact - it's neither positive or negative; aside from the time lost in getting sends up to full volume.
I would suggest that after your weeks break, to restart with about 20-30% of contacts you've already sent to in the previous week(s), who are active i.e. opened your earlier email. You obviously would need to go out with different content to them as they would have opened your Warmup email.
You can then commence bringing in (gradually) the remaining 70% of 'new' records which you didn't send to. It then depends on the quality of your 70%, which I would encourage to only bring in contacts who you know are active / never bounced. Taking this approach will allow ISPs to recognise that your quality is good, that your volumes are increasing.
ISPs recognise patterns of sending, so if there is a weeks break, it's typically recognised that it might be a newsletter being sent, but you're not penalised for taking breaks, but you are penalised for sudden spikes of bounces, so you want to trickle in new subscribers to get rid of the dirty bounce and unsubscribes.