How reliable has alias forwarding been (to external email addresses)
 

I am a Google Workspace legacy refugee considering either paying for Google Workspace or Fastmail. I used to be a Fastmail user a very long time ago (I still remember the good ol' days of doing css templates for the UI).

I love Fastmail's feature set. However, I will definitely be needing to do some alias forwarding. Both Google and Fastmail's forwarding passes DKIM but fails SPF but from the emails I tested, I had not experienced any deliverability issues.

That said, everyone that I will be forwarding email for will be using a Gmail destination address. So I figure using Google to forward to Google is less likely to have deliverability issues. But Fastmail, I am not sure confident.

I know some of the companies that specialize in forwarding (like ImprovMX, which I tried) manage to pass SPF (not sure exactly how they do it), but I don't see any split routing capabilities in Fastmail to allow me to farm unrecognized email recipients to another provider. I would assume POBox.com does it well, which is owned by Fastmail, but their product, whereas it uses the Fastmail webmail, does not have the entire feature set of Fastmail.

Any thoughts/experiences from people who have used alias forwarding extensively?

Thanks!

I have used alias forwarding (to Gmail) as a mechanism for disaster backup in case Fastmail becomes unavailable (as happened recently as a result of a DDoS attack). I am unaware of any delivery issues. However, all the backed up messages go to the same Gmail account, and some messages could be silently discarded, or placed in the Junk folder without me noticing. In general, after initial testing, the only time I access the backup account is when there is a problem at Fastmail.

It seems likely, to me, that Google would learn to trust messages going from Fastmail to specific Gmail accounts on a regular basis. No guarantees.

Thanks for the feedback. I'm hoping it is reliable, as it would be a lot of work to migrate out again if it proves to be sporadic. I can always add a user to the basic plan for $3 a month and have them retrieve mails via POP and then delete from the server, I suppose. I expect that would ultimately be the most reliable, but costs a lot more, especially as the users add up.

I basically keep "family" email domains hosted at Fastmail and forward mail via alias forwarding on those domains to the recipient's primary mail box, mostly to the free Gmail service (so no GSuite etc).

It has been working reliably for about 4 years now (as long as I have been using it). We haven't had any bounced mail, as far as we know.

Ah this is great to know and is exactly how I plan to use it. Thanks!

Oh, I just discovered the SRS rewriting option on aliases. I just enabled it on one of the aliases that forwards to Gmail. The SPF passes now. I think this should work great!

Edit: hmmmm, now I am not so sure. According to Google’s recommendations to administrators, we should not modify the envelope sender. It seems to suggest NOT to use SRS.

https://support.google.com/mail/answer/175365?hl=en

In your case, I would not recommend the use of SRS. For a specific alias, you always know the Gmail recipient. Instead of using SRS, in Gmail, set up a filter that whitelists the incoming address. This will take preference in Gmail, even if a strict SPF policy is in use.

Depending on your domain registrar you can also forward direct from there. I do this with some addresses via Porkbun where the domain is hosted. Works reliably. You can even send emails from Gmail using Google's smtp server using these instructions: https://support.google.com/domains/answer/9437157

Also, it helps if you add Gmail to your SPF record.

Good point! I use v=spf1 include:_spf.google.com ~all

Just recognise the potential for phishing attempts from random Gmail addresses if you do that. My own approach is only to whitelist specific addresses.

Hmmm, but it would be hard to know every sender. Since the sender can be anyone. I guess this can help if there is a known bouncing issue from a particular domain with a strict SPF policy. Is that what you meant? Or do you mean that I can somehow whitelist the forwarding server of Fastmail?

In all the domain registrars I've used, if you use their forwarding service, I would need to point my MX records to them. In this case, I would have Fastmail host my email and have only a few aliases forwarded. The only way to go back to using a domain registrar for only certain addresses is if the email provider has SDR (split domain routing) back to the registar, but Fastmail doesn't have that.

Yea, plus, there is no issue with sending as the domain in this case. Any of the forwarded aliases will never be trying to "send as" the domain. They are simply receiving it. If they needed SMTP, I'd give them a fastmail mailbox or set up a verified SMTP relay.

In the case of a gmail recipient getting an email forwarded through Fastmail from some unknown original sender, I don't think an SPF record for google even helps (google is the recipient)? I know it helps to have the SPF include the Fastmail server, but that's something I already have.

I'm sorry, but I may have confused this thread. I meant that an option for just alias forwarding would be to use your domain registrar. If you also use FM as the main way to send and receive your email it makes more sense to use them for alias forwarding too. You mentioned POBox.com (part of FM) and I found their forwarding service worked perfectly with great deliverability.