mailygo

README

MailyGo

MailyGo is a small tool written in Go that allows to send HTML forms, for example from static websites without a dynamic backend, via email. It can be used for contact forms on pages created with Hugo (example).

MailyGo is lean and resource-saving. It can be installed with just one executable file.

Installation

MailyGo can be compiled with the following command:

go get -u codeberg.org/js32/mailygo

It can then be executed directly, for example like so:

SMTP_HOST=mail.host.com PORT=587 SMTP_PASS=yourpassword SMTP_USER=user@host.com USE_STARTTLS=true EMAIL_FROM=user@host.com EMAIL_TO=otheruser@otherhost.com ALLOWED_TO=otheruser@otherhost.com PORT=8000 ./mailygo

Or you can use an env-file and start the whole thing via systemd service. A blog post for noobz like me will follow.

Configuration

To run the server, you must set a few environment variables from the list below.

Name	Type	Default value	Usage
SMTP_USER	required	-	The SMTP user
SMTP_PASS	required	-	The SMTP password
SMTP_HOST	required	-	The SMTP host
SMTP_PORT	optional	587	The SMTP port
USE_STARTTLS	optional	true	SMTP connection with STARTTLS
SMTP_HELO	optional	localhost	SMTP HELO hostname
EMAIL_FROM	required	-	The sender mail address
EMAIL_TO	required	-	Default recipient
ALLOWED_TO	required	-	All allowed recipients (separated by ,)
PORT	optional	8080	The port on which the server should listen
HONEYPOTS	optional	_t_email	Honeypot form fields (separated by ,)
GOOGLE_API_KEY	optional	-	Google API Key for the Google Safe Browsing API
SPAMLIST	optional	gambling,casino	List of spam words
DENYLIST	optional	submit	List of fields names to deny
TOKEN	optional	-	A token to identify the origin of the submission
MESSAGE_HEADER	optional	-	Text to appear at the beginning of the email message, before the list of fields
MESSAGE_FOOTER	optional	-	Text to appear at the end of the email message, after the list of fields
MESSAGE_SUBMITTER	optional	false	If set to true and the form submitter provide an email address, a copy of the message is sent to him
MESSAGE_SUBMITTER_HEADER	optional	-	Text to appear at the beginning of the email message sent to submitter, before the list of fields
MESSAGE_SUBMITTER_FOOTER	optional	-	Text to appear at the end of the email message sent to submitter, after the list of fields

Special form fields

You can find a sample form in the form.html file. Fields whose name do not start with an underscore (_) will be sent by email. Fields with an underscore serve as control fields for special purposes:

Name	Type	Default value	Usage
_to	optional	-	Recipient, it must be in ALLOWED_TO, hidden
_replyTo	optional	-	Email address which should be configured as replyTo, (most probably not hidden)
_redirectTo	optional	-	URL to redirect to, hidden
_formName	optional	-	Name of the form, hidden
_token	optional	-	Token to identify the origin of the submission, hidden
_t_email	optional	-	(Default) "Honeypot" field, not hidden, advised (see notice below)

As I'm using MailyGo to handle a contact form and I want the fields Name, Subject and Message to be listed on the email in that particular order, I created specific names to handle those fields. Its use is optional. You can use all of them or just one. They will be listed on the email just before the others fields.

Name	Type	Default value	Usage
_name	optional	-	Form submitter Name
_subject	optional	-	Form submitter Subject
_message	optional	-	Form submitter Message

Spam protection

MailyGo offers a set of options to prevent spam:

• A Honeypot field, which is basically another input, but it's hidden to the user with either a CSS rule or some JavaScript. It is very likely, that your public form will get the attention of some bots some day and then the spam starts. But bots try to fill every possible input field and will also fill the honeypot field. MailyGo won't send mails of form submissions where a honeypot field is filled. So you should definitely use it;
• A list of spam words (see SPAMLIST on Configuration). If any of the fields include a word from the list the submission will be marked as spam and an email will not be sent;
• A list of fields names to deny (see DENYLIST on Configuration). Some bots try send a particular field or set of fields that are not part of the form. This is easy to identify and the name of those fields can de added to this list so MailyGo handle those submissions as spam;
• A token to identify the origin of the submission (see TOKEN on Configuration and _token on Special form fields). Some bots will grab the URL of your MailyGo and post a submission directly to that address, bypassing the form. To prevent this, a token can de used to assure only the submissions that come from the form are handle by MailyGo. This token can be any combination of letters and numbers. If a TOKEN is defined on configuration, MailyGo will look for a field named _token. If this field doesn't exist or its value doesn't match the one defined on configuration the submission will be marked as spam and an email will not be sent;
• If a Google Safe Browsing API key is set, submitted URLs will also get checked for threats.

License

MailyGo is licensed under the MIT license, so you can do basically everything with it, but nevertheless, please contribute your improvements to make MailyGo better for everyone. See the LICENSE file.