Everything you need to know (or almost) about the "MailFrom" address!

Hello dear reader, I resume the series of articles I dedicated to the different settings needed to properly send & deliver emails. From the IP configuration to the sender domain, you will find all the good practices that will allow you to have a perfect (or almost perfect) configuration ... After this, no more bad excuses 🙂

Today, we're going to talk about domains and more specifically about the "MailFrom" address. It is important to know what this technical address is used for, where to find it in an e-mail and how to customize it - if your router and your configuration allow it - in order to be DMARC compliant!

The "MailFrom" address... What is it??

When you send an e-mail to someone, two specific addresses will be used:

• The "FROM" address or sender address: it indicates the sender of the e-mail (for example: yesreply@badsender.com for those who have subscribed to our newsletter). This address is directly visible to the recipient.
• The " MAILFROM " or return-path address: it indicates the origin of the message (cf. your sending server). This address is not directly visible by the recipient, he will have to display the SMTP header of the e-mail to see it.

It is important to know that the "MAILFROM" address is also called the "e-mail envelope" or "return address". It will generally be used by the mail servers to send back the bounces (or bounced mails) to the sender.

Please note that the "FROM" and "MAILFROM" addresses can be the same or different, it will depend on your router configuration.

Where to find the "MAILFROM" address in an e-mail??

You have two ways to find this "MAILFROM" address. First of all, you will have to search & display the SMTP header of the e-mail.

The "return-path" address

This is certainly the easiest way to find the "MAILFROM" address in a header, you just have to look for the value contained in "Return-Path:".

Checking the SPF record

If you have read some of my articles on email authentication, you have probably noticed that only SPF registration is not checked on the sender domain or "FROM" domain (unlike DKIM, DMARC or BIMI) but on the "MAILFROM" domain. So, you just have to search in the header for the SPF authentication results and look at the values contained in "smtp.mailfrom" (for most ISPs/Webmails) or "envelope-from" (for Orange)

How to choose your " MAILFROM " address ??

I'll be honest with you, since this is a technical area, it will be managed by your router. Depending on your configuration and the flexibility of the router, you will have two possible configuration choices:

Default configuration

This is the default choice, you will use the router's "MAILFROM" domain. There will be positives and negatives to using a generic domain:

+ You will not have to delegate and set up any parameters.
- You will share the reputation of the generic domain with other advertisers.
- The generic domain will not be DMARC compliant with SPF registration.

Custom configuration

If you want to go further and want to control your reputation & configuration, most routers offer (under condition) to customize the domain name that will be used as the "MAILFROM" address. As with the default configuration, there will also be positive and negative points to using a custom domain:

+ You will use a dedicated domain and its reputation will also be dedicated.
+ The domain "MAILFROM" will be DMARC compliant with SPF registration.
- A delegation and settings will be made.

Generally, on the last missions I have been able to carry out, I have always advised (see push) to personalize this domain name unless a technical constraint does not allow it. For example, if you have a Sendinblue account and you have opted for shared IPs, you will use the generic domain name for the "MAILFROM" address.

I conclude...

I hope to have enlightened you a little more? Feel free to go check your current configuration and see if you too are using a generic or customized "MAILFROM" domain. If you have any questions or if you want to customize your domain name too, contact us 🙂

In the next article, I will show you how to set up a custom "MAILFROM" domain at Sendgrid ! Don't worry, I have the same article planned for other routers 😉

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