smtp server

How To Warmup SMTP Server (Free Warmup Tool Inside)

Are your emails going to SPAM? Don’t worry, It's OK.
It is very common for emails to go land in the spam folder for a new sender with a new SMTP server (Email Server), new IP & Domain.
Even if all technical aspects such as SPF, DKIM, DMARC, RDNS, No Blacklists, and 10/10 Score on Mail-Tester.com are in place, your emails may land in spam.
When you build a New SMTP Server with a new IP Address, or when you subscribe to an SMTP Service Like Amazon SES with a Dedicated IP, and before You can Start Sending any Email Marketing Campaigns, you have to warmup your IP Address.
Also, you need to warm it up if you left your IP without sending any email for more than 30 days or so.
So, SMTP warmup is somehow a continuous process.

What is Warming Up IP?

When you have a new Brand IP Address for your SMTP, this IP will have no Reputation on the internet, and ISPs (internet service providers) don't know this IP. So, IP warmup is the practice of building your reputation on the internet by gradually increasing the volume of emails sent with your IP address according to a predetermined schedule.

When an ISP notices an email suddenly coming from a new IP address, they will immediately begin evaluating the traffic coming from that IP.

Since ISPs treat email volume as a key in determining spam, it is best to start sending a low email volume, then increasing up your way up to more significant amounts.

This gives the email providers a chance to carefully observe and analyze your sending habits and volumes and record how your recipients engage with your email.

In general, Warming up takes between 2-10 Weeks according to your scenario and the number of emails you want to send per day.

How do ISPs evaluate your emails and Reputation?

When you start the warming up process, ISPs will Evaluate your Reputation according to three Main Factors:

1. Bounce Rate: When you send an email campaign, you need to ensure that your emails are valid emails, High bounce rate will destroy your reputation.
2. Spam Traps: Even a very low percentage of spam traps can blacklist you!
3. Spammy Content: Your message content is essential. ISPs will check if you are using any spammy keywords or blacklisted links.
4. User Interaction: How Recipients are interacting with your emails, if they are reporting you as spam, then this is a real problem!

Warming Up IP in Action (Examples)

Ok, now after we have the big picture warming up SMTP, let’s go with some examples and real scenarios and understand how the operation works:

Please note: These sample schedules are intended to be a suggestion only. Every sender is different.

1. 1000 Emails Per Day

This is not a big deal, you start by sending 14 emails the first day, then increase gradually to reach 1K in about 10-15 days. The schedule is described in the following table:

Day	No. Of Emails	Increment Emails Per Day
1	14	0
2	19	5
3	27	7
4	37	10
5	52	14
6	72	20
7	100	28
8	140	39
9	194	54
10	270	75
11	375	105
12	521	146
13	725	203
14	1000	275

2. 10K Emails Per Day

Now, in this scenario, we do the same thing, but with a more extended schedule, check the following table:

Day	No. Of Emails	Increment Emails Per Day
1	13	0
2	16	3
3	20	4
4	25	5
5	32	6
6	41	8
7	51	10
8	65	13
9	82	16
10	103	21
11	129	26
12	163	33
13	205	42
14	259	53
15	326	67
16	410	84
17	517	106
18	651	133
19	819	168
20	1032	212
21	1299	267
22	1635	336
23	2059	423
24	2592	533
25	3263	671
26	4108	845
27	5172	1063
28	6511	1339
29	8197	1685
30	10000	1803

3. 50K Emails Per Day

Now 50K per day is considered somehow a big number.

As a little advice, and to make things easier, always split large volume warmup campaigns into smaller ones, like in our case, we split it into three schedules:

1. Reach 10K emails.
2. Reach 30K emails.
3. Reach 50K emails.

You may say, this will make the warmup schedule longer, maybe yes, but in our experience in this way, you can monitor and manage your warming-up campaigns easily and get better results.

So, if you were warming to 10K, the number of emails would be less, and you can see and monitor the user interaction and bounce rate on a smaller amount of emails, which will make the picture clearer.

I hope you got the point.

Free Warmup Tool

Warmup Schedule Generator

We always try our best to make things easy for everyone, especially for beginners, so we developed the Free Elitetools which also has a simple warmup schedule generator tool

Then, Select Your Email List Size, and Click Generate! And See the Magic

Email Volume and Timeline

For IP warmup, the warmup schedule, and the sending volume is different for all senders.

The number of emails you send depends on your own total email volume, some may require to send 100 emails per day, and others may need 1M per day!

But in any case, you must send enough emails at enough frequency so that your email reputation can be tracked.

Also, you have to know something very important, most reputation systems only store data for 30 days, so you should not go 30 days or more without sending on an IP. If you do, then you will need to warm it up again. This is why we said above that warming up an IP is a continuous process.

Transaction VS Marketing Emails

Transactional Emails

If you want to use your SMTP server to send Transactional Emails (Password resets, invoices, welcome emails…). In this case, you may be an established business or a new business.

Established businesses:

If you are already sending a lot of emails, and you decide to move to an ESP for the first with dedicated IP or build your own SMTP, you should migrate you're sending a little bit at a time.

One way to do this is to split your traffic and move small portions of it to the new IP over time.

Alternatively, if you are already maintaining multiple mail servers, you can move your servers over to your new IP one at a time.

New businesses:

Typically, the organic growth of your business will, by its nature, create an ideal ramp. Since transactional email is usually dependent on the number of users you have, the growth in your customer base will create a nice, comfortable growth curve in your email volume. So you will not worry about warming up in this case.

But still, it's important to monitor your reputation and your system to see how it's performing. (We will talk about monitoring reputation later)

Email Marketing Campaigns

The Simplest Approach is to estimate your total monthly email volume and divide that number by 30.

Then, try to spread your sending evenly over the first 30 days, based on that calculation. For example: if you will send 90,000 emails/month, you should start off sending 3,000 per day over the first month and so on.

Maintain Warmup across ALL ISPs

It’s important to remember that you must maintain a steady volume during the entire warmup period for each ISP.

So remember to split up your warmup schedule so each ISP is receiving a comparable amount of mail each day – don’t warmup Gmail on Monday, Yahoo! on Tuesday, etc. – evenly disperse your mail to each ISP on each day of warmup.)

If not, your sending activity looks sporadic and you won’t be able to build a solid reputation.

Just mix things up! Don't send to one ISP at a time.

Warming up IP Tips:

There are some crucial tips that you have to Follow while warming up IP:

1. Don’t ever start before you get a High sending score: Ensure this by configuring SPF, DKIM, rDNS, and other Technical Details.
2. Don’t ever send promotional emails in the warmup period. You need the highest engagement rates, so send transactional emails or maybe some valuable info.
3. Mail only to your top active subscribers first. Ensure almost 0% bounce rates.
4. Don’t rotate or switch IPs during warmup. Rotation is a sign of spam.
5. In your emails, add a clear link for people to unsubscribe.
6. Add an Email Signature that makes your emails look trusted.
7. Mix your campaigns with premium SMTP services – this will give better user interaction and domain reputation.
8. Join Newsletters. This will make a lot of emails come to your inbox and give you a Higher domain reputation.
9. Send to your friend’s list and ask them to report you as non-spam and tell them to reply.
10. Try your best to build an audience and warmup to that audience. In this way, you will achieve the best user interaction and will make the “warming up process” a lot easier.
11. Monitor your campaigns accurately, and be sure to keep your bounce rate below 2% by validating your emails (You can use our service to validate the emails – Bulk Email Verification)

How to Monitor IP Reputation?

So, you need to monitor your Bounce rate, user feedback, and reputation score.

Some Services Like Amazon SES, and Sparkpost has a built-in reputation system that shows your Bounce Rate and User Interaction.

If you are using a Custom SMTP as we explained in How To Set Up SMTP Server With Postal (Step By Step Guide) or whatever SMTP you are using.

In some cases, you will be able to monitor bounces and user feedback through the mailing system like in MailWizz. You can also monitor open, unsubscribe, and open rates. This will give you an indication of how users are interacting with your messages.

Monitor Reputation?

Having the right tools for checking the IP reputation is halfway to success. Here are some tools and
services you can use:

• senderscore.org by Return Path. The score ranks from 0 to 100, 100 being the best. It tells you how you're performing. Typically it's recommended that you maintain your sender score of 90 or better.
• talosintelligence.com by Cisco. It tells you how your reputation is across all the network providers Cisco manages. The reputation score is grouped into Good, Neutral, and Poor.
• postmaster.live.com Microsoft's Smart Network Data Services gives you information about the traffic originating from your IP address such as the volume of sent emails, complaint rates, and spam trap
  hits.
• postmaster.google.com Gives access to your domain's data on Google Search Console.
• postmaster.aol.com Check your IP reputation and rates it as “bad”, “neutral”, and “good”.

Conclusion:

IP warmup is the act of sending emails gradually to build a good reputation and reach the recipient’s inbox. So, be careful, and follow the guidelines and tips listed above, to achieve the best results.

Good Luck, if you have questions or clarifications, you can comment below, or open a question on Sapnaaz Forum.

Hope You All The Best!

What is a SMTP Server?

Email is among the widely used communication channel, and most internet system uses Simple Mail Transfer Protocol SMTP to transfer email from their server to the recipient’s server.

It’s a standard communication protocol used by mail servers and other message transfer agents and can impact the deliverability of your campaigns.

This guide will discuss what SMTP is and how it works in the email marketing landscape.

What is the Simple Mail Transfer Protocol (SMTP)?

The Simple Mail Transfer Protocol (SMTP) is a technical standard for transmitting electronic mail (email) over a network. Like other networking protocols, SMTP allows computers and servers to exchange data regardless of their underlying hardware or software. Just as the use of a standardized form of addressing an envelope allows the postal service to operate, SMTP standardizes the way email travels from sender to recipient, making widespread email delivery possible.

SMTP is a mail delivery protocol, not a mail retrieval protocol. A postal service delivers mail to a mailbox, but the recipient still has to retrieve the mail from the mailbox. Similarly, SMTP delivers an email to an email provider's mail server, but separate protocols are used to retrieve that email from the mail server so the recipient can read it.

What is a protocol?

A protocol consists of a set of rules and procedures which govern the exchange of data between two or more devices. Protocols define how data transmission will occur between electronic devices such as computers. They set the standard procedures for communication and the exchange of information.

The International Organization for Standardization established the Open Systems Interconnection (OSI). One such widely used Internet protocol lays down the standard for communication over different networks. The model divides the process of data transmission into a series of seven layers.

Important internet protocols are TCP/IP, HTTPS, DNS, and SMTP.

What is an SMTP server?

An SMTP server is a mail server that can send and receive emails using the SMTP protocol. Email clients connect directly with the email provider's SMTP server to begin sending an email. Several different software programs run on an SMTP server:

• Mail submission agent (MSA): The MSA receives emails from the email client.
• Mail transfer agent (MTA): The MTA transfers emails to the next server in the delivery chain. As described above, it may query the DNS to find the recipient domain's mail exchange (MX) DNS record if necessary.
• Mail delivery agent (MDA): The MDA receives emails from MTAs and stores them in the recipient's email inbox.

Common SMTP server providers & settings

SMTP Provider	URL	SMTP Settings
AOL	aol.com	smtp.aol.com
AT&T	att.net	smtp.mail.att.net
Comcast	comcast.net	smtp.comcast.net
iCloud	icloud.com/mail	smtp.mail.me.com
Gmail	gmail.com	smtp.gmail.com
Outlook	outlook.com	smtp-mail.outlook.com
Yahoo	mail.yahoo.com	smtp.mail.yahoo.com

How does the SMTP work?

The Transmission Control Protocol (TCP) is the primary connection for communication between the mail sender and the mail receiver. In SMTP, the mail sender sends the data in command strings over this reliable ordered data stream channel.

The SMTP client, the initiating agent, sender, or transmitter, initiates the communication session. It issues the command strings and opens the session for corresponding responses from the SMTP server, which involves the listening agent or receiver. Zero or more SMTP transactions may be there in a course.

Usually, an SMTP email transaction follows four command or reply sequences:

HELO/EHLO command

It tells the email server that the client wants to start the mail transaction. The client mentions its domain name after this command.

MAIL command

It lays down the bounce address/return address, defining the return or reverse paths.

RCPT command

It specifies the recipient of the message. The sender’s envelope contains the addresses of the recipients, to which the RCPT command can be issued multiple times for each recipient.

DATA

It shows where the content of the message starts, as opposed to its envelope. An empty line separates the message header and body in the message’s text.

DATA is not just one command but a group of commands in which a server has to reply twice

• First, the server acknowledges the message and replies with its readiness to take the message.
• Then after completing the end-of-data sequence, it either accepts or rejects the entire message.

Apart from the reply of the DATA command, the server can reply in a positive way (2xx reply codes) or a negative way.

The negative responses can further be permanent (5xx codes) or transient (4xx codes).

If a server sends ‘reject,’ then it is a permanent failure, and the client needs to send a bounce message to the respective server. On the other side, a ‘drop’ is a positive reply in which the message is discarded instead of delivered.

What is an SMTP envelope?

The SMTP “envelope” is the set of information that the email client sends to the mail server about where the email comes from and where it is going. The SMTP envelope is distinct from the email header and body and is not visible to the email recipient.

What port does SMTP use?

In networking, a port is a virtual point where network data is received; think of it as the apartment number in the address of a piece of mail. Ports help computers sort networking data to the correct applications. Network security measures like firewalls can block unnecessary ports to prevent the sending and receiving of malicious data.

Historically, SMTP only used port 25. Today, port 25 is still in use for SMTP, but it can also use ports 465, 587, and 2525.

• Port 25 is most used for connections between SMTP servers. Firewalls for end-user networks often block this port today, since spammers try to abuse it to send large amounts of spam.
• Port 465 was once designated for use by SMTP with Secure Sockets Layer (SSL) encryption. But SSL was replaced by Transport Layer Security (TLS), and modern email systems, therefore, do not use this port. It only appears in legacy (outdated) systems.
• Port 587 is now the default port for email submission. SMTP communications via this port use TLS encryption.
• Port 2525 is not officially associated with SMTP, but some email services offer SMTP delivery over this port in case the above ports are blocked.

Difference between SMTP, IMAP, & POP3

The Internet Message Access Protocol (IMAP) and Post Office Protocol (POP) are used to deliver the email to its final destination. The email client has to retrieve the email from the final mail server in the chain to display the email to the user. The client uses IMAP or POP instead of SMTP for this purpose.

To understand the difference between SMTP and IMAP/POP, consider the difference between a plank of wood and a rope. A length of wood can be used to push something forward, but not pull it in. A rope can pull an item, but cannot push it. Similarly, SMTP “pushes” email to a mail server, but IMAP and POP “pull” it the rest of the way to the user's application.

What is Extended SMTP (ESMTP)?

Extended Simple Mail Transfer Protocol (ESMTP) is a version of the protocol that expands upon its original capabilities, enabling the sending of email attachments, the use of TLS, and other capabilities. Almost all email clients and email services use ESMTP, not basic SMTP.

ESMTP has some additional commands, including “EHLO”, an “extended hello” message that enables the use of ESMTP at the start of the connection.

Conclusion

SMTPs are essential for sending and receiving emails. However, as an email marketer, you need to choose and configure the SMTP service providers that suit your requirements.

At Sapnaaz, we provide easy SMTP setup and integration with any SMTP servers you might like to send your email marketing campaigns. Feel free to reach out to the Sapnaaz team to learn more or check out our SMTP setup service page.