How to set up aliases

"Alias" is a commonly used term for an additional email address. Aliases are helpful if you want to have different email addresses without creating multiple users: for example, if you are a business owner, you could have a sales@mydomain.com alias for sales inquiries, and a press@mydomain.com alias for news inquiries.

• How to create an alias
• How to edit an alias
  • Delivery options
  • Compose options
• How to delete an alias
• Catch-all aliases
• How many aliases can I have?
• Masked Email
• SRS rewriting

How to create an alias

You can create an alias by following these steps:

1. Go to Settings → My email addresses and click Add address.
2. Select the first option, Create an alias.
3. Enter the alias you'd like. If you want to change the alias's domain, you can click the dropdown menu and select the desired domain. You can choose from custom domains that have been set up in your Fastmail account, or you can choose from Fastmail's domains. When you're ready, click Create alias.
4. A new screen will appear where you can choose a name, delivery options, and other settings for the alias. (You can go back later and change these settings if you need to: see the Editing an alias section below.)
5. Be sure to click Save.

If you are an admin looking to create an alias for another user in your account, this can be done by going to Settings → Users & Sharing → Aliases.

Note: Aliases can take up to 15 minutes to take effect.

How to edit an alias

You can make changes to any of your aliases by going to Settings → My email addresses, finding the alias in the list, and clicking the corresponding Edit button. From this screen, you can edit the alias's delivery and compose options.

Be sure to click Save after making changes to an alias.

Delivery options

Delivery options allow you to control how you receive mail that is sent to this alias.

With address actions, you can automatically take action on incoming mail for each alias. Choose from the following options:

• Take no action: Messages will be delivered to your Inbox as normal. Mail rules will take effect.
• Move to a folder / Move to a label: Messages will be delivered to the selected folder/label. Mail rules will take effect after this action is applied.
• Deliver to another address:  Messages will be delivered to the selected address.
• Delete to trash: Messages will be delivered to your Trash folder. Mail rules will not take effect.

You can also set a description to remind you what the alias is for, and see when the alias was last used to receive mail.

Advanced delivery preferences

The following options will appear if you click Show advanced delivery preferences. We strongly recommend leaving these settings unchanged unless you are an advanced user.

• Alias delivery target: Aliases must have a target address in order to receive mail. By default, an alias's delivery target is your Fastmail username address. The target can be changed to deliver mail to any other user, including other Fastmail users or a completely external email address. An alias is also able to target more than one address.
  • Note: If your alias targets more than one email address, each recipient will count as one email sent for your account limits. As an example, this means that if you have one alias that points to three different email addresses, each email sent to this alias will count as three emails sent.
• Also send to all contacts in: If you have contact groups set up, you can use this option to deliver mail to a particular group.
• Disable: If you no longer wish to receive mail at a particular alias, but you do not want to free up the alias by deleting it, you can disable it instead. (This is helpful if you have a catch-all alias set up in your account that is receiving unwanted mail at a certain alias.) Once the alias has been disabled, any further email sent to that address will bounce and return to the sender as undeliverable.
• SRS: You can enable SRS rewriting for email sent to an alias. We don't recommend enabling SRS unless you need to (for instance, if emails aren't being forwarded correctly).

Note: If you are using a custom domain, please ensure that the domain is configured to have Fastmail handle mail delivery. This goes for both the custom domain that the alias is using, and the custom domain that the delivery target is using.

Compose options

Compose options allow you to control how you send mail from this alias.

• Name: The name that recipients will see on messages you've sent from this alias.
• Hide this address when composing messages: If this option is enabled, this address will not appear as an option when sending a message unless you click Show all. (This option may be helpful if you receive mail at a large number of email addresses, but you don't use a lot of them for sending mail.)
• Signature: The signature that recipients will see on messages you've sent from this alias.

Advanced composing preferences

The following options will appear if you click Show advanced composing preferences. As noted above, we strongly recommend leaving advanced settings unchanged unless you are an advanced user.

• Reply to: If you want to send messages from this alias, but you explicitly want replies to your messages to go to a different address, you can set that email address here.
• Auto Bcc: If you want messages sent from this alias to automatically Bcc a different address, you can set that email address here.
• Save sent messages in: By default, sent messages will be saved in your Sent folder. If you don't want your sent messages saved in your Sent folder, you can choose the folder here. You can also select whether or not to save messages sent in a third-party email client.
• Nickname: You can add a nickname that will show when you need to select an email address from a list. The nickname will only be visible to you. This option can be helpful if you need to quickly tell apart addresses when composing a message.

How to delete an alias

You can delete an alias by going to the Settings → My email addresses screen. For more information and complete steps, please see the Deleting an email address section of our My email addresses help page.

If you are an admin looking to delete an alias for another user in your account, this can be done by going to Settings → Users & Sharing → Aliases.

Once the alias has been deleted, any further email sent to that address will bounce. Another user could potentially create the alias in the future if it is at a Fastmail domain.

Catch-all/Wildcard aliases

If you have a custom domain set up in your account, you can set up a catch-all alias at Settings → My email addresses, which allows you to receive mail at any address at your domain. Please see our Catch-all/Wildcard addresses help page for more information.

How many aliases can I have?

Accounts can have up to 600 aliases, plus 15 for every user in the account. More details on limits can be found at our Account limits help page.

Note: Accounts on our legacy plans have different alias limits. Please see our Legacy plan details help page for more information.

Masked Email

If you want to create a new email address to use when subscribing to services online, consider Masked Email. You can automatically generate a unique masked email address to receive and send messages, so your real email address remains hidden.

SRS rewriting

If you have rules or aliases forwarding mail to an external target (in other words, a non-Fastmail email address), and the target server uses SPF to block emails, SRS rewriting helps to make sure the external address actually receives your forwarded mail.

We don't recommend enabling SRS unless you need to (i.e., if your emails aren't being forwarded correctly).

SRS rewriting can be enabled or disabled as a team setting. This means that if you are part of a multi-user accounts, enabling or disabling SRS rewriting will affect all users in your account.

You can enable SRS rewriting for all users in your account by following these steps:

1. Go to Settings → Users & Sharing → Team settings.
2. Find the SRS section and click the toggle button next to Enable SRS rewriting. Changes will save automatically.

How SRS rewriting works

SPF is a way for domain owners to authorize only particular servers to send email with a certain SMTP MAIL FROM envelope. The problem is that when email is forwarded by a service, the SMTP MAIL FROM envelope should be preserved. When that happens, it looks like the forwarding service is trying to send email with the same SMTP MAIL FROM envelope as the original service, which is blocked because the forwarding service hasn't been authorized. This is a problem with the design of SPF.

As an example, let's say you have the alias abc@fastmail.com, and it forwards mail to your other email address, xyz@gmail.com:

1. Someone sends an email from their Yahoo account def@yahoo.com to abc@fastmail.com. The email has an SMTP MAIL FROM envelope of def@yahoo.com and an SMTP RCPT envelope of abc@fastmail.com.

2. We accept the email and see it is an alias with the target xyz@gmail.com. We forward the email with the SMTP RCPT TO envelope of xyz@gmail.com, and by default preserve the SMTP MAIL FROM envelope of def@yahoo.com.

3. Gmail looks at the SMTP MAIL FROM envelope and sees @yahoo.com. Gmail does an SPF check and sees that the IP address of the sending server belongs to Fastmail. Fastmail isn't authorized by SPF to send email with an SMTP MAIL FROM envelope of @yahoo.com. It therefore rejects the message, as SPF has broken forwarding.

When you activate SRS, we change the following:

• We accept the email and see it is an alias with target xyz@gmail.com. We forward the email with the SMTP RCPT TO envelope of xyz@gmail.com, and we alter the SMTP MAIL FROM envelope of def@yahoo.com using SRS rewriting. This creates an SMTP MAIL FROM envelope of something similar to SRS0+abcd=Cw=yahoo.com=def@srs.messagingengine.com. Since @srs.messagingengine.com is a domain we control, there will be no SPF issue, and the message will be forwarded correctly.

• If for some reason the email ends up bouncing, the bounce message will be sent back to SRS0+abcd=Cw=yahoo.com=def@srs.messagingengine.com, which we'll receive. We will then unwrap the rewritten envelope, and send the bounce back to def@yahoo.com.