I had yesterday the problem that exim created for one address an
SRS-hash for one outgoing address that included two dots like A0..XF.
That meant that several mail-servers including gmails didn't accept the
mail because the mail from: wasn't RFC5321-compliant (see RFC 3696 for a
readable version what is and isn't allowed in a mail-address: "period
(".") may also appear, but may not be used to start or end the local
part, nor may two or more consecutive periods appear"). Is there any way
to force exim to not generate a base64-hash that includes "."? It
shouldn't include them in the first place afaik because according to RFC
4648 there is no period in the base64-table and from what I've found
there is only a modified base64-table that uses a period when you deal
with XML.