A domain warmup process is a must if you want to send bulk emails with fewer problems. Since receiving mail services keep an eye on domain reputation to reduce spam, it is important to have a domain that has been warmed up. Otherwise, the deliverability rate will be worse.
On average, it takes about one month to warm up a new email domain, though if you plan to send fewer emails or not send them as frequently, the sending reputation buildup might take less than a month.
While warming up a domain, it is recommended to follow certain practices. First, start with a low sending volume and increase it gradually. For example, if you send 10 emails on the first day, wait for a couple of days and send 20, then 40, and so on. Wait three to four days before you increase the sending volume.
If possible, target recipients who are likely to respond positively. Positive engagement does wonders for a new email domain reputation.
Finally, if you notice that the warmup results are not meeting your expectations, increase the idle period to more than three or four days.