Shared vs dedicated IP for email: which one do you need?

When you send email through a sending platform, it goes out from an IP address that receivers rate. That address is either shared with other customers or reserved for you. The choice affects your reputation, your costs and how much work you take on. This guide explains the tradeoffs using what the major email service providers and M3AAWG publish, and helps you decide which fits your volume.

What is the difference between a shared and dedicated IP?

The M3AAWG Sender Best Common Practices define both:

• Dedicated: "a distinct entity has exclusive use of and responsibility for the outbound mail through that environment." It can be one IP or several, but only one sender is responsible for it.
• Shared: "more than one distinct entity is assigned to an IP environment," either a single IP or a pool of IPs.

An "entity" can be a company, a brand within a company, or a single customer of an email service provider.

On most platforms, shared is the default. Amazon SES says that when you create an account, "by default your emails are sent from IP addresses that are shared with other SES users." SendGrid says its Trial and Essentials customers send from groups of shared IP addresses.

How do shared and dedicated IPs compare?

Sources: Amazon SES's dedicated IP comparison, SendGrid's dedicated IP documentation, and M3AAWG.

What are the advantages of a shared IP?

No warm-up. Mailgun's IP guidance says even a clean IP must be warmed gradually. A shared pool already has history, so you can send from day one.

Steady volume without your effort. M3AAWG explains that IP reputation is "sensitive to changes in sending volume," and that combining several senders' mail in a shared environment helps "sustain consistent overall average sending volume." If you send a newsletter once a month, that steadiness is hard to achieve alone.

Diluted mistakes. M3AAWG says that with many senders in one environment, "mistakes made by any single sender in the environment can dilute the overall reputational impact."

Lower cost. M3AAWG notes that shared environments are typically less expensive, "which makes mailing for very small businesses economically feasible." Amazon SES includes shared IPs in standard pricing and charges extra for dedicated IPs.

What are the risks of a shared IP?

The same pooling cuts both ways. Google's sender guidelines say: "The activity of any senders using a shared IP address affects the reputation of all senders for that shared IP address." SendGrid says that if anyone sharing your IP violates a provider's standards, "your reputation changes as well," and your messages can be throttled or blocked.

M3AAWG warns of "a greater chance that the poor sending or list-building practices of one entity can 'poison' the environment." Good providers manage this:

• SendGrid says it groups your account "with senders of similar reputation and deliverability."
• Amazon SES says it "carefully manages the outbound traffic to maximize the reputations of the shared IP addresses."
• M3AAWG recommends that each sender in a shared environment DKIM-sign with its own domain or subdomain, so receivers can tell senders apart.

That last point is why your domain matters even on a shared IP. Sign with your own domain, and your reputation travels with it.

When does a dedicated IP make sense?

M3AAWG lists several situations:

• Your mail is better than average, and you want to protect it from other senders' reputation.
• Your mail quality is unknown or worse than average, and the provider wants to isolate it from others.
• You want control over volume. M3AAWG says "consistency of volume, whether high or low, plays an integral part in the determination of IP reputation."
• You want full responsibility for your reputation, your own reverse DNS, or third-party certification that requires a dedicated IP.

How much volume is enough?

Providers state different markers. Use them as guides, not rules:

Amazon SES adds an exception: dedicated IPs can work at lower volume when you send to a small group of recipients whose servers accept mail by IP allowlist rather than reputation.

If your volume is irregular, Amazon SES says its managed dedicated IPs are the better option among dedicated choices, because they warm up and scale automatically.

What does a dedicated IP require from you?

A dedicated IP isn't set-and-forget.

1. Warm it up. Amazon SES says email providers "are less likely to accept mail from new IP addresses that have little or no history," and that warm-up can take from around two weeks to six weeks depending on the provider. SendGrid's automated warmup needs at least one other warm IP to carry overflow traffic. Our guide to warming up a new domain or IP covers a cautious ramp.
2. Keep volume steady. Amazon SES advises sending around 1,000 emails a day to each provider you want to keep a positive reputation with, after warm-up.
3. Own the monitoring. SendGrid says that with a dedicated IP, "you have the responsibility of monitoring and maintaining its reputation and listing status." Check it regularly with the Blacklist Checker and register it in Microsoft SNDS.
4. Set brand-specific reverse DNS. M3AAWG recommends that reverse DNS for a dedicated IP identify the sender, not just the provider. Check it with the PTR Lookup and see our reverse DNS guide.
5. Separate your streams. Yahoo's best practices say not to send bulk or marketing mail from the IPs you use for user mail, transactional mail and alerts. Google says that if you must use several IPs, use a different one for each message type.

What about your everyday business mail?

The shared-or-dedicated choice applies to mail sent through an email service provider or your own mail server. It doesn't apply to the messages your staff send from Microsoft 365 or Google Workspace mailboxes. Those go out through the provider's own sending infrastructure, and you don't pick the IP.

What you control there is the same thing that matters on a shared IP: your domain. Publish SPF, turn on DKIM signing with your own domain, and publish DMARC. Our email deliverability checklist covers the domain settings in order.

How do you choose?

Answer these in order:

1. Do you send large volumes on a regular, predictable schedule? If not, stay on a shared pool.
2. Is your list permission-based and clean? A dedicated IP will show your habits plainly. Fix bounces and complaints first; see hard vs soft bounces and spam complaint rates.
3. Can you warm it up and monitor it? If no one will watch logs, blocklists and Postmaster Tools, a managed shared pool is safer.
4. Do you need a fixed, known IP? Some partners allowlist by IP. That can justify a dedicated IP even at modest volume.
5. Is your domain authenticated? Whatever you pick, sign with your own domain using DKIM and publish SPF and DMARC. Check them with the SPF Checker.

For most small businesses, the answer is a reputable provider's shared pool with your own domain's DKIM.

Next steps

1. Find out which kind of IP each of your sending platforms uses, and whether it signs with your domain.
2. Send a test from each platform to the Email Deliverability Test to confirm SPF, DKIM, DMARC, reverse DNS and blocklist status.
3. If you move to a dedicated IP, plan the warm-up before the first send and split marketing from transactional mail.
4. If you send business notifications from your own systems, iBlockSpam's outbound relay DKIM-signs them, with 500 messages a month included. It's built for business mail, not bulk campaigns.
5. If mail is already landing in junk, start with why your emails are going to spam.

Browse more guides on running email day to day.