SMTP Server is a part of the application layer of the TCP/IP protocol. Using a process called “store and forward,” SMTP moves your email on and across networks. Similarly, it works closely with something called the Mail Transfer Agent (MTA) to send your communication to the right computer and email inbox.
SMTP spells out and directs how your email moves from your computer’s MTA to an MTA on another computer, and even several computers. Using that “store and forward” feature mentioned before, the message can move in steps from your computer to its destination. At each step, Simple Mail Transfer Protocol is doing its job. Even so, this all takes place behind the scenes, and we don’t need to understand or operate SMTP.
Using an outgoing SMTP server is the traditional method of sending emails. An alternative solution to bypass SMTP server and directly send to destination. It is also known as direct send which is not very reliable because :
- Cannot be used if port 25 is blocked by our ISP.
- It is unfit for bulk email due to multiple connections of different servers.
- Cannot send non-personalized emails.
- It can be blocked by email filters because emails are not sent from regular SMTP server
Pros and Cons of a Local SMTP Server
- No daily and hourly limit on the number of outgoing emails
- Instant reporting
- Privacy and control of all our outgoing mail
- No shared IP
- Running a local SMTP server takes time and effort
- the bounce rate may increase by 20-30%
- It is insecure as hacking can be easily done.
- Server limitation
Requirements For a Local SMTP Server
There are no specific type of requirements but we should prepare for the following:
1. Some ISP’s may block the port 25. We can solve this by contacting our ISP provider and learning about the limitations they impose. Also, we need to request a correct DNS server and permission for MX record resolution.
2. For bulk emails, we should opt for a domain and fixed IP address associated with it. This will increase our resistance to spam filters.
Is an SMTP Server Good for Testing?
Especially in most cases, people set up local SMTP servers for testing purposes. If we are developing an app which sends emails. We need to test this function.A real SMTP server running on our local machine might seem to be a good option. But is it? On one hand, it’s not troublesome to install and configure a local SMTP server. However, there are much better solutions.
If we use Mailtrap for testing, we will get an advanced tool based on a fake SMTP server. It means that our app will send emails but won’t actually deliver them. Our outgoing mail will end up in the Mailtrap Demo inbox. So, we need not to worry about real email recipients and checking the spam folder each time we run tests. No installation is required at all. Therefore, all we need to do is update our SMTP settings with Mailtrap credentials. Alternatively, we can copy and paste a ready-to-use code snippet. Different integrations are available for common frameworks and programming languages.
SMTP sometimes stands for “STOP”
Our Internet Service Providers have a limit to the number of emails we can send out over a certain amount of time. Most of the time, it is limited to a set number per hour or per day.
Also each ISP relies on its SMTP to determine the email which can be sent out by one connection. (It is a protocol ). For some people who work at home or manage large mailing lists can be a problem. After they hit their limit, finally the ISP will simply stop sending emails. If they think we are a spammer, they might even shut down our account.
Clearly, email limit varies by ISP. For example, the typical Comcast Cable Internet customer is limited to 1,000 emails per day. (Their business customers have a limit of 24,000 emails daily.) Verizon and AT&T do it differently. Moreover, they put a limit of 100 on the number of recipients we can have on one sent email.
Obviously, running a local mail server can sometimes be a pain. A great deal of knowledge and effort is require for achieving good email deliverability using our own SMTP server. Whereas, it is a good option for testing purposes.