Applies To: Cloud-managed Fireboxes
SMTP (Simple Mail Transport Protocol) is a protocol used to send email messages between email servers and also between email clients and email servers over a TCP connection on port 25 or 465. You can add the SMTP and SMTPS traffic types to a cloud-managed firewall policy to control email messages and email content. For more information about how to add and edit traffic types, go to Configure Traffic Types in a Firewall Policy. This topic describes the policy settings you can configure for SMTP and SMTPS traffic.
You can also configure content scanning for SMTP traffic with Gateway AntiVirus and spamBlocker. For more information, go to Configure Content Scanning in WatchGuard Cloud.
SMTP Settings
You can configure these settings for the SMTP and SMTPS traffic types.
If you include both the SMTP and SMTPS traffic types in the firewall policy, when you change the settings for one of these traffic types, the change also applies to the other traffic type. For example, if you set Maximum Email Size to 25 MB for the SMTP traffic type, the Maximum Email Size value automatically updates to 25 MB for the SMTPS traffic type also.
Maximum Email Size
To set the maximum length of an incoming SMTP message, type the maximum size for each email in megabytes. The default value is 20 MB.
Most email is sent as 7-bit ASCII text. The exceptions are Binary MIME and 8-bit MIME. 8-bit MIME content (for example, MIME attachments) is encoded with standard algorithms (Base64 or quote-printable encoding) to enable them to be sent through 7-bit email systems. Encoding can increase the size of files by as much as 40%. Make sure you set your maximum email size to consider the size of encoded messages. The Firebox rejects messages that exceed the configured limit.
Configure SMTP Settings
To configure the SMTP settings, from WatchGuard Cloud:
- Add the SMTP or SMTPS traffic type to a policy. For more information, go to Configure Traffic Types in a Firewall Policy.
- In the Traffic Types list, click SMTP or SMTPS.
Or, click
next to the traffic type and select Edit Settings.
The SMTP Settings dialog box opens.
- Configure the settings described in SMTP Settings.
- To save the changes, click Update, then click Save.