Email Delivery 101

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Email Delivery vs Deliverability


"Can a receiver accept your message?"

The term “Email Delivery” describes whether or not an ISP or receiver accepts your email, which comes before the inbox or spam folder distinction. If your email doesn't make it into an inbox, that means delivery wasn't successful, no matter which inbox it would be displayed in.

Delivery refers to whether or not a receiver accepts the message you’ve sent. Does the domain or email address exist? Is your IP address blocked?

Similarly, when an email is successfully delivered, that simply means it made it to the intended recipient’s mailbox — and that could be in the inbox or the spam folder.


"Does it get to the inbox?"

Also known as inbox placement, this is a term that describes where that message ends up once it is delivered: In other words, deliverability decides if your email will land in the inbox, spam folder, or another folder.

When an email doesn’t make it to the inbox it has “Bounced”, but not all bounces are made equal.

Types of Bounce

Hard Bounce

A hard bounce means that you tried to send an email to an invalid address (one that doesn’t exist). If you get lots of hard bounces, it’s a signal to ISPs that your mailing list isn’t very clean. You can clean up your list by doing an email validation.

Soft Bounce     

A soft bounce can occur for a couple of reasons. In the past, you might get soft bounced if you try to email someone with a full inbox. These days, most email service providers offer much larger inboxes, so this is rarely the reason for a soft bounce.

Most soft bounces today occur when there is a sudden increase in email sending volume. If you typically send 500,000 emails per day, then one day suddenly send 700,000, those extra 200,000 emails might be soft bounced. ISPs like consistency, and don’t like sudden changes.

How ISPs affect email delivery/deliverability

Sending limits

For every emailer, ISPs establish a sending limit. This is the amount of email that they believe is acceptable and normal for you to send in some set amount of time. Once you reach your sending limit, ISPs will soft bounce all the emails you try to send afterwards until the limit resets.

For some senders, this might be a weekly sending limit. For others, it might be a daily sending limit. This depends on the volume of emails you send regularly. How strict the limit depends on your sender reputation. But no matter how good your reputation is, if you create a huge spike in sending volume, your emails will get soft bounced.

How do you manage sending limits?

If you want to avoid having your emails soft bounce, you need to slowly ramp up your email volume. Let’s say you want to run a huge Black Friday campaign, with a big increase in email volume. You should start slowly ramping up your email volume at least 30 days in advance. Do this by gradually increasing the volume of your sends, so that you’ll reach your target volume in time for your Black Friday campaign. 


A block means you can’t send any emails. Not good news. ISPs typically block senders after receiving too many spam complaints, or if a sender hard bounces too many emails. A block can last indefinitely, but they are usually in the range of two days to one week. 


Denylisted IP addresses cannot send any emails to any ISPs that filter emails based on that denylist. It’s a stricter form of a block, and it lasts until you appeal with the denylisting organization and are removed from their list.

It is much easier to avoid winding up on a denylist than to try and remove yourself from one. If you are on a denylist, it needs to be your number one priority to get off of it. You will need to demonstrate better sending habits and an improved mailing list, which are good practices anyway.

Factors that affect Delivery

Now we have covered how the ISPs affect email delivery, we can focus on what the ISPs are looking at when deciding how to treat your email. There are multiple parts to this problem but here we will cover sender reputation, one of the most important factors in email delivery.

Sender Reputation

Sender reputation is made up of a combination of two factors: IP reputation and domain reputation. These are calculated separately, but they both have a big impact on deliverability.

What is IP reputation?

All emails are sent from a computer or a server that has a unique identifying address (their IP address). It’s easy to tie this IP address to specific senders, so an IP address gives ISPs a straightforward way to track senders. 

IP reputation is based solely on the IP address where the email originated from. It’s not connected to the brand that’s sending the email. IP reputation is what gets you into the recipient server. As a mail sender, you typically either have a dedicated IP address, or you send from a shared IP pool.

How to maintain a good IP reputation

Once you have established a sending pattern, consistency is key. ISPs will often soft bounce emails if they are anomalous to your existing sending patterns. If you need to send a large volume, it’s always best to connect with your Beamery partner to discuss how to best organise the campaign. 

In order to protect your reputation we will throttle how much you can send to keep it inline with your established pattern. 

If you do not send from an IP for ~45 days your reputation will effectively lapse and you will need to re-introduce your self to the ISPs with a warmup phase.

What is domain reputation?

Domain reputation is what gets you into the inbox. Unlike IP reputation, domain reputation is all about the brand that’s sending the email. 

Domain reputation can follow your brand even if your IP address changes, or you change your email service provider. This can be a good thing if you’ve spent a long time building a good reputation. Part of your domain reputation is your industry vertical. 

In general, domain reputation is concerned with what type of sender you are. Are you new to an IP address? Do you send mail to inactive accounts? Do less engaged audiences get fewer emails? Do you purchase lists and hit spam traps? These are all factors that determine your domain reputation.