Email Marketing

Deliverability FAQs in a time of uncertainty

We’ve summarized a few common email deliverability questions and scenarios to consider.

Over the last two weeks, we’ve been working with email marketers that have found themselves in uncertain times. These uncertain times come with rapid changes to email communication plans, some of which can drastically affect email deliverability. While there are a wide variety of unique scenarios and questions to address, we’ve summarized a few common questions and scenarios for you below.

Meet the expert
Kathleen Schaefer
Kathleen Schaefer
Senior Director, Inboxable

Kathleen Schaefer is the Senior Director at Inboxable. Kathleen is a leader in email and cross-channel digital marketing solutions. She focuses on leading and maintaining client facing support for Data Axle/Inboxable technology and service offerings. Kathleen’s expertise allows her to help Data Axle clients to conceptualize campaigns, recognize capacity and achieve successful outcomes.


If I reduce sending volumes for the time being, what should I be keeping in mind for deliverability?

  • As you make decisions on how your communication plans will change, you want to ensure there’s a balance between altering communication plans and maintaining a level of consistency – both with your subscribers and with the receiving ISPs.
  • ISPs closely rely on your sending volumes when scoring sender reputation, and their systems come to expect send patterns from each domain and IP. Suddenly changing your communication plans can have adverse effects on your sender reputation if those altered plans drastically change your send frequencies or send volumes.
  • Keep in mind that any significant reduction in send volume, even though a temporary one, may create the need for a “re-warm up plan” to get your send volume back up to your regular send volumes once the pandemic is over.
  • If you decide to lower send volumes by narrowing the email audience you send to (for example, only mailing to your highest engaged subscribers temporarily) make sure not to lose sight of the subscriber experience for those temporarily not receiving email or receiving less email than they were previously accustomed to.
  • Communicate your plans with your subscribers so that they know what to expect. This way, when you return to their inbox it shouldn’t come as much of a surprise and you’ll reduce the risk of spam complaints or unsubscribes when returning to regular email communication plans.

Are there any implications to halting email communications altogether?

Yes. These implications can be broken down into three silos, which are all closely connected: ISP reputation, spam complaints and list hygiene.

  • ISP Reputation: If your domain and IP go completely silent the ISPs will gradually stop storing reputation metrics and your reputation will go “cold”. Losing your sender reputation can cause an increase in spam folder placement and ISP blocking once you return to sending email communications. The longer you halt email communications altogether, the longer your reputation warm up period will need to be when you come back online.
  • Spam complaints: Aside from the fact that going silent with email can cause reputation to be lost, halting your email communications can also pose risk that your subscribers become disinterested with your email program altogether and start to feel disconnected from your brand. When you start email back up, this can pose risk to elevated unsubscribe and/or spam complaint rates as some subscribers no longer feel connected.
  • List Hygiene: There’s some risk that email accounts in your list may be abandoned and closed while you’re away from their inbox, and when you return to their inbox their address could cause an increase in your total hard or soft bounce rate. There’s also potential that some email addresses have converted to an ISP spam trap address (if you halt email for a long enough timeframe). If you can find a way to deliver value to your subscribers, even at a lowered email frequency, you provide yourself the ability to receive bounce backs from those abandoned accounts and process them out of your list through your ESP soft and hard bounce rules.
  • If you halt communications, plan for a warm up phase: IP warming is unique to each email program, especially within unforeseen circumstances like we’re facing today. It’s always best to consult with a deliverability professional on the right IP warming plans coming out of a slowdown in volume. They’ll make sure that your past and current sender reputation is factored into whatever IP warming plans you may need, since this shouldn’t necessarily be approached in the same way a new domain and IP warming plan would be approached (ex: migrating email service providers).

Can I send important deployments to audiences outside of our normal targeting (less engaged subscribers) without impacting my deliverability and sending reputation?

No. Despite these unique circumstances, any time you are sending to less engaged subscribers you pose the risk of elevated bounce rates, spam complaints and spam traps. There are some steps that you can take, to keep your deliverability risk at a minimum, and we have outlined them here.


Since we are looking to reduce volumes during this time of crisis, would now be a good time to tighten targeting to highly engaged subscribers as a reputation rebuilding initiative?

If your team is planning on reducing the reach of each email communication, it is an ideal time to focus on your most engaged subscribers/purchasers as an effort to keep engagement up and solidify your sender reputation with the ISP community. This will ensure that you continue to have a line of communication with your priority subscribers and customers, while also ensuring your ISP reputation doesn’t disappear. If you’ve been dealing with any reputation issues prior, take this opportunity to send very targeted communications to your subscribers that will help boost your engagement metrics (particularly marking your email as ‘not spam’ and engaging positively from the inbox with frequent opens and clicks).


I'm decreasing our email communications - is there a minimum cadence or send volume I should use to preserve my reputation?

Minimum send volumes and frequency recommendations should be approached on a case by case basis, as these are all relative to what your email program looks like on an average day. To help you approach your email program, here are some example scenarios:

  • Scenario 1 – We have roughly 1M active email subscribers that typically receive daily promotional content. We are reducing that to weekly promotional frequency for the time being due to the ongoing pandemic. Are there any deliverability repercussions to this change?​
  • No, given the fact you’re keeping up weekly frequency to your 1M subscriber base, you shouldn’t experience any major loss in sender reputation. ISPs will adjust once you eventually pick back up with your daily cadence, and they’ll already be familiar with your volume of 1M being sent on a weekly basis. With at said, some deliverability challenges can surface if your subscribers get comfortable with weekly cadence and then you suddenly return to daily cadence after you decide to do so. A gradual ramp up in your mailing frequency will help minimize any risks associated with heightened spam complaints or unsubscribes, ensuring your subscribers don’t get surprised with cadence returning to normal after settling in at weekly emails.
  • Scenario 2 – We typically send only a monthly newsletter to our email subscribers but have decided to put this on pause and return to monthly cadence once the pandemic subsides. Are there any deliverability challenges with this?
  • Yes, given the fact that ISPs start to stop tracking sender reputation statistics after 30 days of zero email traffic, you may face increased scrutiny from the ISP community when you come back after hiatus and begin sending again. You face some risks with losing familiarity and brand recognition to your subscriber base as well, given the length of time you’ll potentially be silent over the email channel. This can pose some added risk to spam complaints, ignored email rates and unsubscribes when you return to your subscribers’ inbox. If you do decide to pause email communications altogether, here are a few tips:
    • Communicate your plans – notify your subscribers of your plans to go quiet over email before doing so
    • If possible, increase your social media presence to help bridge the gap with your close followers that utilize both channels to engage
    • Put together a re-warm up volume plan to avoid surprising the ISP community when you re-surface

For more specific scenarios you are faced with, please reach out to us for advice and recommendations. Every change in send volume and send frequency is unique and each sender faces different challenges depending on how you are configured with your ESP (shared IP pool vs. dedicated IPs), your domain reputation and history, and your existing reputation with the ISP community. We’re here to help you evaluate where your sender reputation sits today, understand how changes to your email communication plan will affect your deliverability, and give you guidance on choosing the right plan that minimizes risk to your reputation as a sender long term.

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